Both plants do the same thing; boost clicking power. Thumbcorn is literally your first mutation, so one would expect the later Glovemorel to be superior; at first glance it does -seem- better, with double the clicking bonus.
However, when I tried to use it, I found two problems. First, by the time most of them are mature, many of them have already expired due to intensely random growth and a very short mature life. Second, the CPS penalty actually becomes large enough that they aren't better than thumbcorn in the first place! While it varied wildly, I'd get about +180% click bonus and about -30% cps. That's 280% total click power and 70% production, which turns into about 196% click power compared to normal.
But a field of thumbcorn... gives +90% click power already! They're cheaper, mature much faster, and stay mature long-term. With RNG, it's very likely a glovemorel field will actually give -less- click power than the thumbcorn!
So, it'd be nice for glovemorels to get either more click power, or a lower cps penalty, to where they're actually usable. Along with perhaps a slightly more forgiving maturation time...