What is internal and external fertilization

Internal fertilization "when you have to parents and they join their sperm and egg together and you develop inside your mother"

External fertilization "when you only have one parent that fertilizes their own egg but you are not developed inside a mother ex (frog)"
The advantage of external fertilization is you are formed and "birth" out quicker but you would look exactly like the parent that birthed you like a copy as a clone.

The advantage of internal fertilization is you don't look exactly like your one parent but you get features from both parents and it takes just a little bit longer to develop like 9 months.