My understanding is that enum types allow setting a column to one of several specified values, while set types allow selecting one or many.

When running a query on SQL Server that fetches columns through a linked MySQL server, MySQL fields of ENUM type have additional whitespace at the end if they are not the longest string in the enum. I ...

I think varchar is pretty universal but I'm mostly familiar with mysql and can't say for sure. It seems like SQL server and postgres have varchar though so maybe it's ok.