That is incorrect. In vi and vim, "ESC" is the key that puts you into command mode (from insert mode). Command mode is the full-screen visual mode where you enter commands by a sequence of keypresses.
":" is the key which issues "ex" commands. vi and ex are two different modes of the same editor. Any command which begins with a colon is an ex command, not a vi command, not done in "Command Mode".
":" is the key which issues "ex" commands. vi and ex are two different modes of the same editor. Any command which begins with a colon is an ex command, not a vi command, not done in "Command Mode".