They seem to be pretty far apart for anyone to be thinking of drafting wahlstrom ahead of tkatchuk
They really shouldn't be.
Production at the same age:
USHL
Wahlstrom: 14GP-13G-8A-21P
Tkachuk: 24GP-11G-12A-23P
US U18 Team
Wahlstrom: 36GP-29-21A-50P
Tkachuk: 61GP-25G-29A-54P
Stats are somewhat skewed in Wahlstrom's favour, as he gets to play with future top pick Jack Hughes, while Tkachuk led his team in scoring and didn't play with the same kind of talent, but still that much of a difference in production indicates that Wahlstrom is the better offensive player at the same age.
And like Tkachuk, Wahlstrom is a very toolsy player. Real solid kid at 6'1, 205lbs, skates very well and has a terrific shot. He's got a ton of qualities you look for in a goal scoring winger.
Tkachuk has more hype because:
a) he's a year older, so naturally he looks more impressive in the same season
b) he had a really good WJC - the biggest stage with a ton of eyes watching
c) his last name is Tkachuk, and his brother has blown expectations out of the water thus far
Overall, they are probably on the same tier as prospects, and picking one over the other shouldn't be surprising at all.