Think of WLM as WM + bug fixes + Hotmail access.
Other differences are largely cosmetic.
There are a few basic differences. WLM works on both XP and Vista.
WLM doesn't have a unified Inbox, it sets up separate mail folders
for each mail account.
WLM is receiving the benefit of ongoing Microsoft development
while WM is not. Unlike here, Microsoft reps participate in WLM's
newsgroup.
There is no drawback to trying WLM. If you decide you don't like
it, you merely uninstall it, and WM is back.
Gary VanderMolen