run by vs. run past

Hi everyone,

I have a question to a native user of English, because I'm not sure if I, as an ESL speaker, can tell the difference. I was wondering if there is any difference between these two in the following sentences:

1. a) Can I run these figures by you? vs. b) Can I run these figures past you?

2. a) We had the contract run by our employees. vs. b) We had the contract run past our employees.

Is there a difference in meaning between a) and b) in each case?

I'd really appreciate your help. Thank you.
Gregory