Both work exactly the same - they increase the quantity of what you hold, and the invested money (cost-basis) is included in the principal.
I think that DRIP still increases your IP. If not for reinvestment, you would hold that cash in hand - it didn’t come from nowhere.
The only distinction in C for Buy & Transfer is at the taxes level. All tax presets look only at the Buy & Sell, as transfers generally don’t have tax implications.