A VPN is built for privacy on one device: everything goes through one server, and you keep that one address until you switch. A proxy is built for control: you choose which program uses it, which country it exits from, and whether each request gets a new address.
That is why automated work uses proxies. A scraper needs thousands of addresses, an antidetect browser needs a different one per profile, and neither is possible with a single tunnel. A proxy does not add encryption of its own; https sites stay encrypted between you and the site either way.
Read next: Which kind of proxy to choose