If I work in East Lansing,MI fulltime the whole year of 2020, but I live in Williamston,MI (a 20 min drive away roughly), am I a nonresident or resident to East Lansing?

You are a non-resident of East Lansing - you live in Williamston and are, therefore, a resident of Williamston.

As a non-resident of East Lansing, you will pay a 0.5% tax on earnings made in East Lansing.  Residents (working in East Lansing or another community) will pay a 1% tax.