ELI5: The difference between normal queues and DQ.

I was wondering what the real difference is.

Both have MMR/ELO and try to match you based on that, one is hidden one is not.

What else? Isn't it essentially the same queue twice now, just one gives end of season rewards? Couldn't they of just replaced "normal" games with DQ and kept the other rank systems in place so the people playing normals got rewards and could rank up while playing with their friends?

Personally, I seem to remember stopping playing normals around 3k games in because I got tired of being in queues with groups and felt helpless in those games. I don't get how this isn't casualizing ranked mode, maybe I'm missing something.