1) The term ‘emoji’ came along with the Japanese emoji on the iPhone. Nobody at the time called MSN/forum emoticons ‘emoji’, so it’s a neologism to say that MSN had emoji.

2) Emoji are a fixed, standardized set that works the same way across the entire OS. 2000s emoticons were implemented separately on each app and website, with differing support and designs everywhere.

Some contemporary apps (like Slack and Discord) choose to override the system emoji style and provide their own shortcodes though, so I guess they are like a hybrid of emoji and traditional emoticons.