6 types of Bitcoin addresses (in parentheses are the data they keep):
P2PKH 1... (a public key's hash)
P2SH 3... (a script's hash) (defined in BIP16)
SegWit (P2WPKH/P2WSH) nested in P2SH (defined in BIP141)
P2SH-P2WPKH 3... (a public key's hash)
P2SH-P2WSH 3... (a script's hash)
(these start with three because these addresses are meant to be ...
Not enough funds usually means that you've confused the unit of account i.e. mbtc vs. btc or you're not accounting for transaction fees including 2fa fees if you have a 2fa wallet. I suggest you use the exclamation point in place of a numeric amount to see what is the max amount you can send. Decoding the generated transaction should be illuminating.