short n simple
Awakening valk: has vacuum, fast unprotected movement (echo walk), usable ult/bsr,
feels more like create/wait for an opening due to gaps. Feels more passive/insta burst

Succ Valk: Has protected CCs, CCs hit multiple times, feels more like you can actually play the game by cycling defenses while attacking. Feels more aggressive, slower, but still hurts.
Both: They both have hard hitters and are usable. Honestly just play which ever one you enjoy.

Tbh, I enjoy succ more, awakening was fun pve wise, but boring pvp wise. Pretty much hide behind the shield, drop vacuum, if they get stuck or CC'd, drop terra. If not either wait 25s, or try to CC them with unprotected skills and most likely die.