A. No, both features are measured differently. 

The time parameter of "months", is based on the logic of a "week" being classified as 7 days. So in this case, 1 "month" would be 4 weeks or 28 days. 

When using the "days" parameter, you can set the exact amount of days you want the cohort builder to look back. 

Note: Both options are great tools to use when defining your audience.