Why would some historians regard the GI Bill as a "success" and why would others regard it as a failure?

Because the GI Bill was successful for only part of the population.

Explanation:

GI Bill is a law passed in 1944 promoted to help soldiers mobilized during the 2nd world war to rejoin in the society. The benefits that the soldiers would have are; financial aid by a year, facility to obtain loans of a house or small business and financing of its technical or university studies. This economic drive led to economic and social development between 1950 and 1960.

However, even though the law intended to help all soldiers, there was discrimination and segregation when it was granted; African American soldiers and women were less benefited, or had greater obstacles to obtaining benefits; for example, universities did not allow people of color to enroll, and they were not granted financing to purchase housing.

For this reason, the GI Bill was a success for white soldiers returning from the war, but it did not equally benefit the entire population, with African Americans and women being discriminated against.

I hope this information can help you.

i don't know why don't you google it?

the difference is that white collar worker performs skills like worker as a scientist or well blue collars do physical work and they do services like being a cook.