I've been shooting WMT and WME for many years - since a brick of WMT was $15. I've found that some guns like one and some like the other. There's also a slight difference between lot numbers like all rimfire ammo.
One difference is the speed... from the Sinclair International site:
" Wolf Match Target has a 40 grain bullet and a muzzle velocity of 1,050 fps. Match Extra has a 40 grain bullet and a muzzle velocity of 1,033 fps."
I always suggest starting with the cheap ammo, you might get lucky and find something your gun likes.
If you are shooting for group size, the Extra seems to throw fewer flyers, but the WMT isn't bad at all and the flyers aren't way far outside the group, just enough that one might ruin a 1/2" group at 50.
John