Quick question: "Balance transfer" or "purchase"?

I paid off a very catalogue purchase using a credit card only a few weeks back, is a purchase, I have also made catalogue payments in the past which all counted as purchases.

These are what have not counted as purchases for me.

ATM withdrawal (obvious)
Payments to gambling sites.

These have counted as purchases
Paying off hitachi loans over the internet. (buy now pay later items)
Paying off catalogue items (again buy now pay later items)
Paypal transactions funded by credit card.

Unknown
Sending money on paypal. A recent transaction where I sent my sister £300, has cash advance next to it on the statement, yet to see any interest for this appear tho waiting for next statement. I have done 3 other paypal transactions to her which all counted as purchases so this one is odd if counted as cash. It is possible the cash fee is for another transaction (betting) but just delayed on statement.