In terms of HTML the “when to use this as opposed to that” is one of those things that often either isn’t relevant or doesn’t make a lot of sense in the small, limited context of the early challenges. It really comes into play when you’re building a whole page or component. Whether it’s through trial-and-error, conversation with other members of the community, or your own research, you’ll start getting a handle on this as you start your front end projects. An example that comes immediately to mind: a couple days ago someone was asking for help with positioning text and the answer was “If you want to use
display: inline on text, you should put it in a
span instead of a
p because a
p consumes the full width of the parent.” That sort of thing isn’t going to make much sense in a “Here’s the paragraph element” challenge.
I do strongly encourage you to look up the html elements that you are learning with resources like MDN. That will give you a much more extensive “typically used for” or “differs from the other thing by” explanations.
ETA: And it’s always a good time to ask! Whatever lingering “when” and “why” questions that you have after looking at a longer description of an element, feel free to come start a discussion in the forum!