THE WORDS sieve and strainer are often used interchangeably, but they are actually two different culinary tools with very different functions. Strainers are used to separate solids from liquids. When you pour a pot of hot water and pasta into a colander, you are straining the components. A sieve is used to change the texture of a food. The ingredients are passed or pressed through the mesh of a screen or the holes of a metal disk. The size and texture of the food particles are completely changed.

There are three types of sieves worth considering that are available in the United States -- the drum sieve, the chinois and mechanical sieve attachment. The oldest style is the drum sieve. Originally made of wood in a classic drum shape and often called a tamis, it is used primarily to sift flour, sugar and other dry ingredients for baking.

Drum sieves are constructed of two wheel rim disks with mesh stretched between them. They look much like embroidery frames. The rustic models have horsehair mesh which functions well but cannot re replaced. More modern versions use interchangeable nylon grids.

I use a teardrop shaped wooden sieve for dusting flour on my pastry board. The design allows a comfortable one-handled grip. But wooden sieves, either round or teardrop, are not very sanitary or sturdy. Thick mixtures will break down the frame and pungent foods will be absorbed by the wood. They are really more decorative than functional and are priced from $12 to $25.

Professional quality aluminum drum sieves, however, are excellent for big jobs. Made with a tinned steel replaceable mesh, these 16-inch diameter utensils allow the food to spread out over a large surface. You can push the ingredients through with a broad flat comfortable motion and they are strong enough to hold up under the heaviest of purees. Like most restaurant supply items, they are not inexpensive, but at $50 to $60 you get your money's worth.

Another sieve first produced in France reminded everyone of the hats worn by Chinese coolies and immediately became known at a chinois, the French word for Chinese. It is a cone of mesh or perforated metal. The cone is clipped onto the rim of a bowl or pot and held in place with a long handle. The food to be mashed is placed into the chinois, and a wooden pestle, also shaped like a cone, is used to press the ingredients through the holes in the chinois. When selecting a chinois, look for one with as few seams as possible. Welded seams, skinny rims and narrow crevices collect particles of food and make the utensil difficult to clean. Make sure there is a clip or other suitable device for holding the sieve onto the rim of the bowl or pot and that the handle is sturdy and well attached to the cone. The point at which the handle is connected to the cone takes a great deal of pressure, and one with cheap welding will soon come apart. Also, the handle should have a hole for hanging, otherwise storage of this tool will drive you crazy. Stainless steel is the best material because of its resistance to interaction with high acid foods. Make sure the chinois you choose will fit inside your pots.

The best hand operated tool for sieving is the Mouli Food Mill. Made of tinned steel that will not interact with foods, it has always looked to me a bit like the lunar landing module. The ingredients go into a bowl perched atop three legs. A curved blade is rotated over the perforated base of the bowl forcing the food through the holes. The size of the final product is controlled by the selection of the base disc in the bowl. There are three interchangeable discs -- fine, for thin, pureed consistency, medium for smooth vegetable soups and coarse for ricing potatoes. It separates skins, cores and seeds as it mashes, sending only the final product to the bowl below. Jammed particles can be freed by merely reversing the direction of the blade.

The foods that are sent through this device have a texture I find far superior to the baby food mush or uneven chop that results from some of the poorly designed food processors that are in such wide distribution these days. The Mouli Mill, which is available in 1-, 5- and 8-quart capacities, retails for $13, $27.98 and $94.98 accordingly.

If you have a Hobart KitchenAid mixer or a Kenwood, you will be able to purchase attachments for these units that will automatically perform the basic sieving functions. The KitchenAid unit is $22, and the Kenwood is $35. If you decide to make jams, jellies or other preserves in quantity these mechanized units will quickly prove their worth.