So I'm just confused. I've read that when writing を is used, but when talking お is used. Is this true or are they entirely different?
You need to distinguish spelling and pronunciation. You do this all the time in English: you're aware that two ("one plus one") and too ("also") have the same pronunciation even though they're spelled differently.
Likewise, in Japanese, keep in mind that the particle を is always spelled を, even though its basic pronunciation is the same as お.
を and お used to be distinguished in pronunciation, but they merged about a thousand years ago. The distinction was retained in spelling for a long time after, just like how in English we still write knight even though no one pronounces the k or gh anymore.
But the distinction in spelling didn't last forever. After World War 2, Japanese spelling was finally revised and every word with を was re-spelled with お instead. をとこ became おとこ, and so on.
Every word except one! The particle を.
For some reason, the spelling reformers decided to keep the particles は, へ, and を rather than re-spell them わ, え, and お. You'll just have to memorize this. There are some other ways Japanese spelling is different from pronunciation, for example in long vowels:
王 （おう） king (pronounced like オー) 追う （おう） chase (pronounced like オウ)
You'll have to keep the differences between spelling and pronunciation in mind as you learn Japanese.
Although every Japanese dialect has lost the distinction between を and お, there are some people who pronounce を as /wo/ today as a spelling pronunciation. You'll also hear a /w/ inserted in some phonetic contexts such as after ん /N/, but this insertion isn't phonemic—that is, it isn't used to distinguish を from お. Likewise, you'll often hear を as /wo/ in songs, but you'll also hear singers insert /w/ before お, so you can't rely on the presence of /w/ to distinguish お and を in modern Japanese, even in songs.
Regardless of any phonetic variation, the particle を is always spelled を.