Meron iba na 33 characters yata, but there's no difference otherwise. Also meron mga shorter, like 16 characters, yung mga ginamit sa ibang physical bitcoins, but those are special and I don't recommend you try to create or use those otherwise. Stick to "normal" length addresses.
Okey na yung mga starting with 1 or 3, yung 3 is just multisig, or pay-to-script, but mostly multisig.
eto galing sa wiki:
Some Bitcoin addresses can be shorter than 34 characters (as few as 26) and still be valid. A significant percentage of Bitcoin addresses are only 33 characters, and some addresses may be even shorter. Every Bitcoin address stands for a number. These shorter addresses are valid simply because they stand for numbers that happen to start with zeroes, and when the zeroes are omitted, the encoded address gets shorter.
Several of the characters inside a Bitcoin address are used as a checksum so that typographical errors can be automatically found and rejected. The checksum also allows Bitcoin software to confirm that a 33-character (or shorter) address is in fact valid and isn't simply an address with a missing character.
Anu po ibig abihin ng multi sig sir? Yung na observe ko lang pg yung starting ay 3 is nag iiba yung address. Bali nag gegenerate ng new add. Gaya ng xapo. Pero sa coins.ph add ay hindi po..