They are virtually the same to fly, the main difference being flaps.
The C152 goes to 30° flaps, whilst the C150 has 40° - making for much more entertaining short-field landings! Also the flap control switch is ungated on the C150, so needs a little more mental effort to operate.
I *think* that the cockpit is slightly smaller on the C150.
Apart from that, most differences are engineering rather than piloting. It's no effort really to go straight from one to the other so long as you take 2 minutes to think about the flap control - although I'd personally recommend that a less experienced pilot flew a couple of 40° flap approaches with an instructor before trying on their own.
G