In QuickBooks, a customer is a Customer, but in YOUR business it may be something different. You might call them a Client or a Student (if you run a school). If you have a non-profit organization, you may want to call them Donors. I can also call them Sponsors, Payee, or just generally Business. As a gag, I was playing around and changed the "name" for a client to "Dirtbag." The result reads kind of funny when you do that. The point is that you can call them anything you want so you can customize the experience specifically to your business type.
QuickBooks doesn't let you do this.
The little things matter, especially as time goes on and your business grows, you are going to want to be able to hire and train people to use your project management software with the shortest possible learning curve. If they are accustomed to calling customers "Clients" then you want the option to have that nomenclature available so it all just makes sense.
Let's see what this looks like.