I remember in USA, college also 4 years

College Diploma. A little less than a degree.

大专 = vocational school 大专文凭 Vocational School Diploma

I think the term for 大专 is junior college, but I'm not sure really. If it is, then, a junior college diploma(or certification): 大专文凭、大专毕业证书 have received a junior college education: 受过大专教育；大专学历 a junior college graduate: 大专毕业生 I don't think a junior college graduate holds a degree.

Bachelor's degree.