Passively DCA’ing VOO over SPY?

I’m in my mid/late 20s and for whatever reason I originally chose SPY as my long term ETF to pump surplus money into. I’ve seen people consistently mention VOO over it. I’ve amassed six figures in SPY and am a bit worried about tax implications of selling all of it to move it to VOO.

Is there any major difference between the two or would I be safe continuing to pour my money into SPY? Would it make sense to just put all future funds into VOO?

Thanks in advance, sorry, as you can tell I’m a novice investor who just just wants to retire before I die 🙂