A tibble is an improved version of a data.frame. You can read about them here:
You do not have to worry about the differences most of the time. They are usually made by reading in data from a file or a data base, rather than entering the data manually as in your example.
You see the function above (which is actually tribble, since it's transposing a tibble) a lot here in community since it's a visually friendly way of pasting in some example data to make a data frame/tibble. At least when I do this, it's usually by way of the datapasta package (I have a little blog post, below, explaining how to use datapasta with reprex to make minimal examples)