Spinks has credited Minecraft as direct inspiration. Terraria was first released among the gobs and gobs of minecraft clones, yet it was obvious that Terraria wasn't a clone.
As for "Full Release", Terraria was first released as a fully working game, with it's 1.0 being the first public release in May 2011. Minecraft 1.0.0 was November 2011. Minecraft's first public release was Classic 0.0.11a in May 2009.