The two congresswomen from Prince George's County, where the issue of school busing has led to years of rancorous debate, played markedly different roles yesterday as the House defeated a proposed constitutional amendment prohibiting all busing for racial balance.

Republican Marjorie Holt, whose district includes the southern areas of the county where antibusing sentiments are strongest, was chosen by her colleagues to lead the unsucessful last-minute effort to save the measure.

Democrat Gladys Noon Spellman's position was somewhat more ambivalent. An outspoken opponent of busing, Spellman joined the effort to bring the amendment to a vote, then decided to vote against it.

Earlier this week Spellman said that she had backed the effort to get the amendment out of committee "not so much to end busing but to draw the attention of Congress to the fact that the [the busing issue] is smoldering. . . . we should be looking to come up with other alternatives."

The actual wording of the amendment proposed by Rep. Ronald M. Mottl (D-Ohio) "is atrocious," Holt said."It doesn't do what it sets out to do." And a measure as important as a constitutional amendment should not be tinkered with just before a final vote, she added.

After the vote yesterday, Holt said she was surprised at Spellman's final decision to oppose the amendment. A number of congressmen, she said, backed the effort to bring the bill to a vote, "then when the chips are down, they aren't there."

The problems with the language of the original amendment appeared by last week to be crippling any chance of its success. On Tuesday, members of the Republican Policy Committee, after hearing several long complaints about the wording, decided not to support the measure.

Mottl and another chief backer of the amendment, Rep. L.A. (Skip) Bafalis (R-Fla.), then approached Holt and asked her to draft alternative wording that could be subsituted for the original language when the amendment came up for consideration.

Bafalis said yesterday that the group approached the Maryland congresswoman because she had led earlier antibusing fights in the House and "her identity with the subject is strong." In addition, he added, "she's not offensive or abrasive on an emotional issue like this. Some other people are."

When Holt rose to offer the alternative language in the middle of the debate yesterday afternoon, she condemned busing in general then detailed what she called the "madness" of busing in Prince George's.

The speech mirrored the predominantly conservative feelings of the residents of her 4th District, which includes not only southern Prince George's but most of Anne Arundel County, where many families moved to get away from busing.

By contrast, Spellman's 5th District includes not only such white middleclass neighborhoods as Bowie and New Carrollton, where antibusing sentiment is strong, but also most of the predominantly black inside-the-Belt-way communities whose residents brought the suit that led to the mandatory busing plan in 1973.

"Gladys was caught in the middle," one county politician said yesterday.

Votes of the other Washington area members of congress on the constitutional amendment banning school busing for racial balace were:

No: Barnes (D-Md.), Fisher (D-Va.), Harris (D-Va.).

Yes: Bauman (R-Md.).