You're right, both are free and if somebody hasn't tried either yet, I would say download both.
I had played 2048 first so when I tried Threes, it didn't feel right to me at all. If I had tried Threes first, I probably would have had the opposite opinion.
Some of the rules are slightly different (I don't remember how), but the two games are pretty similar. Other than rule differences, the sounds in Threes were very grating to me. I ended up muting all of the sound effects and music. One huge plus to 2048 (IMHO) is that it was released as open source.
I had played 2048 first so when I tried Threes, it didn't feel right to me at all. If I had tried Threes first, I probably would have had the opposite opinion.
Some of the rules are slightly different (I don't remember how), but the two games are pretty similar. Other than rule differences, the sounds in Threes were very grating to me. I ended up muting all of the sound effects and music. One huge plus to 2048 (IMHO) is that it was released as open source.