Job Description for EB2 between employers

[nkt1415]

Hi,

I have a question in terms of GreenCard in EB2 process.

I have below questions on GC in EB2 process:
1. If I get my I-140 approval from Company A, then if I move to Company B, then how far the Job Description used by Company A will influence my H1B extensions with Company B beyond 6 years Cap?
2. If I get my I-140 approval from Company A and then I move to Company B, then how far the Job Description should match between the Company A's PERM and Company B's PERM?

Thanks in Advance