They are different skills. They take different energy and are different thought processes.
In a group setting, you have to target the middle of the pack, but make sure you have movements that are easy enough for the beginners and options that are challenging enough for fitter participants. Since you don’t have health histories for your attendees, there’s a set of contraindications for group fitness that keep most people safe.
In a personal training setting, all of your energy goes into customizing a program for one person and getting the most out of that person.
Personally, I do both. I started in group exercise, and then started doing small-group training, and added personal training for clients who wanted more direct, customized, fitness training. For me, it’s been perfect. People get to know me in my large group-ex classes and then when they take my small-group classes or they train with me, they already trust me and know my training personality so my close % and retention are relatively high.