“Some” VPNs offers a private IP address. Doesn’t that defeat the purpose of a VPN (if you want privacy)?!
You might need to switch between normal VPN IP and a dedicated IP say if you’re trying to stream Amazon, Netflix, etc. or shop on Amazon or other websites that block certain VPN IPs. It’s not your actual IP but also everything done on it is identified with that specific IP if someone can figure out it’s you.
Do you mean dedicated IP address instead? If yes, then it is an improvement because shared VPN IP addresses usually detected by 3rd party detection services such as IP2Proxy. A dedicated VPN IP address can bypass detection for a period of time.
For your information, private IP address is meaning an address reserved for local area network (LAN). It is not suitable for VPN purpose if you are connecting from public IP address.
Pretty much summed it up. Some of those are just gimmicks anyway to get a few more bucks out of the buyer. Most VPN IPs (private/dedicated included) will easily be detected by sites like IPQualityScore.