To some extent, yes. An etransfer can't be reversed at all. I know this because I was that idiot who let his guard down and paid for something in etransfer once (small sum of money at least) and was scammed. I called the bank relentlessly, interac, etc. and was told that once an etransfer is sent, it's sent. There's no undoing it, there's no reporting it as fraud and having it reversed, nothing. In the banks own words, etransfer was the equivalent of handing someone money in person and when they have it, it's theirs unless they give it back.
PayPal has a couple different ways to pay, and most people will pay you using "Goods and Services" payment type. That type of PayPal payment is protected by PayPal's buyer protection guarantee. So if the person doesn't like the item they bought from you, is a scammer, etc. then they can file a dispute with PayPal, who is known to side with the buyer, and PayPal will forcibly take the money back from your account and give it to the buyer. Now they have the item, and their money back too. That being said, if the person does this a lot, then PayPal will obviously catch that type of behavior. The dispute also has some back and forth, so if you put up a really good argument then PayPal may actually side with you and you keep the money, but they are known in general to side with buyers.