What is the difference between the i and a commands of the vi editor?

A.
i (interactive) requires the user to explicitly switch between vi modes whereas a
(automatic) switches modesautomatically.

B.
i (insert) inserts text before the current cursor position whereas a (append) inserts text after the
cursor.

C.
i (independent rows) starts every new line at the first character whereas a (aligned rows) keeps the
indentation of the previous line.

D.
i (interrupt) temporarily suspends editing of a file to the background whereas a (abort) terminates
editing.