Elaborate? In what ways are they similar other than minor details? You both mine, build and fight, but they emphasise different things, and are very different in terms of gameplay imo
Wait, why would you compare two games from two completely different genres? That's like comparing a horror game to a puzzle game, or a rap song to a country song.
They are absolutely nothing alike.
To answer the question, I used to play minecraft back when it was in pre-alpha and played for some years after that. I've been terraria for a long time, but not as early as mincraft, and I have about 500 hours clocked on it. 1.3 is love <3
So basically I liked both, but I don't play minecraft anymore because it makes me nauseous and I hate creepers. I wouldn't mind them if when they blew up blocks, it'd refund every block, and not just 50% of them. You can't rebuild like that.
I like Terraria more because it's 2D, easier to explore without getting lost, and better dungeons and bosses. Building and creating on a 2D world also feels really nice.
I'm not a huge fan of Minecraft and it's survival mode. It ends up becoming boring after lacking amount of bosses and dungeons. I end up switching to creative mode after a while. However, I wouldn't exactly know how much new stuff is added as I played during 2015.