The real difference among fast-food restaurants, claim some adults, is whether you want your meals offered by a clown, cowboy, colonel or a king. A burger is a burger is a burger, right?

Wrong, according to a panel of five young experts who found both subtle and glaring differences in the food and ambiance of five area burger chains. The 9-, 10- and 11-year-olds, who attend the summer program at Rose Park Playground, 26th and O Streets NW, each noon hour for a week sampled the fare at a different fast-foodery.

The cheeseburger connoisseur was Harold Robinson, 10, who loves scary movies. Quarter-pound hamburger expert Donna Golden, 11, likes word games, and double-burger gourmet Eric Poryles, 9, is an avid sports fan. Aspiring tennis pro Teresa Guevara, 9, was chicken and fish critic, and Bullets booster Sebastian Aubouin, 10, sampled the "specialty of the house" at each eatery.

Each critic rated his or her specialty item and all reviewers critiqued side orders and drinks. These judgments were used to select the "best bites" in each category, The young tasters also gave each meal a letter grade (A-E), used to tabulate the restaurant's final rating. Here are their candid-if unscientific-observations on each restaurant, listed in order of preference:

Burger King, A

The townhouse-style Burger King at 1606 K St. enchanted the critical crew who called the two-story design "neat" because they "got to sit way upstairs."

But it was the "humongous" size of the hamburgers and the "perfect" french fries that netted "the king" a straight-A rating from the entire panel.

Donna found the whopper ($1.19, 650 calories) well-cooked and hot, but a bit too thick on the mayonnaise. Harold said the "stuff" (lettuce, tomato, onions, mayonnaise, ketchup and pickle) on the whopper with cheese ($1.39, 760 calories) was "the best of any place." Teresa called fish filet in the whaler ($1.09, 660 calories) "just right."

While most burger chains' double hamburger is two small burgers among three slices of bread, the double whopper ($1.88, 850 calories) contains two large (3.7 oz.) burgers without the addition of that middle slice of bun. The result was "the best, biggest sandwich," according to double-burger expert Eric. Sebastian, who selected as specialty-of-the-house the double whopper with cheese ($2.08, 970 calories), agreed.

The french fries got high marks for their length and crispness (although Eric noted there were a few "flabby" ones). The shakes were the right thickness and the apple pie had "real good" filling. The onion rings, offered at none of the other restaurants sampled, were "wonderful, but there should have been more," said Teresa.

McDonald's, A -

The nonsmoker's section at McDonald's 1401 K St. location drew appreciative raves from the panel, who complained of the "yucky smoke" at other restaurants.

"Everything looks very clean and the food is hot," noted Donna, who said her Quarter Pounder (94 cents, 420 calories) was cooked properly and "not soggy with sauce." Harold's Quarter Pounder with cheese ($1.04, 520 calories) was "cooked just right and very juicy." Teresa's Filet-O-Fish (70 cents, 400 calories) was "too small," but had "a nice taste and good tartar sauce." "The Big Mac ($1.00, 540 calories) has the right amount of lettuce and secret sauce," said Eric, adding that the sauce tasted suspiciously like ketchup and mayonnaise. Sebastian's Happy Meal ($1.41)-which included with cheeseburger, cookies, Coke and fries, a toy watch and top-was pronounced good, but the cheeseburger was "too small" and he needed a second to fill up.

The sundaes were called "delicious," but Donna commented that cookies stuffed in the ice cream were "out of place" and detracted from the taste.

Gino's, A -

The salad bar, crispy fries and fast service at Gino's 40 North Glebe Rd. location pleased the panel, but they would have liked "less noise" and "no flies."The Sirloiner (95 cents, 441 calories) was "good and hot, but dry," said Donna. "And they should let you put stuff on it yourself." Harold felt the Sirloiner with cheese ($1.05, 532 calories) "was cooked just right" and tasted "great."

Eric thought the cheese and meat on his Giant (99 cents, 569 calories) were "pretty good" and Sebastian "loved" his Heroburger-shaped like a submarine sandwich-($1.25, 738 calories).

Teresa was disappointed that no "extra crispy" chicken was ready when the panel visited, but liked her chicken and fries Special ($1.79, chicken drumstick, 136 calories, and breast, 283 calories).

The fries were "crisp," the salad bar "wonderful," but the soft drinks had "way too much ice."

Roy Rogers, B +

One major flaw at the Roy Rogers on 1226 Wisconsin Ave. NW pulled the cowboy's grade down from an A to a B. There was no bathroom. Our distinguished panel had to grab unfinished shakes and fries and run to a theater next door to beg use of the facilities. Unsettling and undignified.

Donna, however, liked "the crispy lettuce and other stuff you can put on your hamburger" ($1.09, 425 calories), as did Harold, who piled onion, ketchup, pickle and tomato on his cheeseburger ($1.19, 475 calories).

Sebastian makes his own specialty at Roy Rogers, what he calls a "Sebastian Super Roy Rogers Burger"-with horseradish and barbeque sauce, ketchup and mustard-one of his favorite sandwiches.

The drumstick and breast ($1.24, no calorie-count available) were "tender and cooked just right," said Teresa. The combination of ham, hamburger and cheese on the Double R Bar Burger ($1.35, 565 calories) was declared "perfect" by Eric.

The fries were "a bit too salty," the Coke had "too much ice" and the shakes were "too thick to drink through a straw." However, the apple cheese crisp dessert was "real good" with a "good mixture of tastes."

Burger Chef, B

Top raves went to the bacon bits on the salad bar at Burger Chef's 1216 18th St. NW location. They found their way onto Harold's cheeseburger as well as salads.

The only way to get a cheeseless large hamburger at Burger Chef is byordering a Super Shef ($1.25, 540 calories) without cheese, which may take a few minutes and costs the same as one with cheese. Donna said it was "smushed" and "not juicy enough." But Harold called it "just the way I like it" after he added pickles and lettuce from the "works bar."

Eric thought the hamburgers were "too thin" on the double cheeseburger (99 cents, 430 calories). With a crowded line, a pleasant but harried clerk and no pictures as guides, no one realized he could have ordered a Big Shef ($1.05, 540 calories), Burger Chef's version of a double hamburger in a three-piece bun.

The Fish filet (89 cents, 600 calories) had, according to Teresa, "just enough tartar sauce" and was "cooked just right." Sebastian enjoyed his Fun Meal ($1.29, hamburger, drink, fries, surprise dessert and toys) and pronounced the balloon, bike reflectors, iron-on patch and card trick both "neat" and "a little too young for me."

The blue-cheese dressing was voted "terrific," as was the entire salad bar and the works bar, but the french fries were "lifeless."