Well it's PayPal without the fees.
I can't think of any fees I've ever paid to PayPal other than for eBay transactions and the like -- though it's of course possible Venmo has different rate structures and thresholds.
My understanding is that (other than the brand and parent ownership) as services they're quite different.
With all of them, you can find a way to use it for free. Eg, if the service you use doesn't support free bank transfers, you link it with a debit card for free transfers.
https://www.digitaltrends.com/mobile/paypal-vs-google-wallet...