It depends, of course. Many townhomes (including mine) are characterized as condos, and generally that results in a slightly higher rate. Also usually an HoA fee, which you may or may not have in a detached single-family home.

In terms of value appreciation, it really just depends on all the normal stuff like location and supple/demand and whatnot. Might be a bit slower than otherwise similar detached houses in the area, might not.