The difference between general bundles and custom bundles are as given below:

1. In general Bundles, you can not add the quantity of the products. But in the custom bundle, you can add a quantity of the products.

2. When you install the bundle app you will see the general bundles by default in your product pages without adding a code(if you did auto-install correctly), but to display custom bundle you need to paste custom bundle code where you want to display.

3. You can change the layout of general bundles(except quantity bundles) but in the custom bundle, you can not.

General Bundle(product, variant, quantity bundle):

Custom Bundle: