HTTPS vs VPN; they are two different things but both serve the purpose of your Internet protection. In fact, both should be used together when surfing the web as they cannot be substituted for one another.
HTTPS also stands for Hypertext Transfer Protocol Secure. You can tell when a website is HTTPS by the padlock next to the URL bar. HTTPS provides secure authentication of the website and its associated web server in order to prevent man-in-the-middle attacks.
Every website you surf on will begin with HTTP, but not all will have HTTPS. Select websites or webpages like your email, online banking, or ecommerce sites usually have HTTPS, especially on a Check-Out page where you need to enter personal information like your name, address and credit card information. The S will only appear to signify it is secure on this portion of the website which is encrypted.
This is done through something called SSL (Secure Socket Layer) which is a certificate the website provides. The website owner purchases it and puts it into their program to shield your raw plaintext data so that your sensitive information will be encrypted.
Source: Tech Hive
A Virtual Private Network is a service you can use to protect your online data and identity when you browse on the web. A VPN is technically made up of a group of computers (or discrete networks). With a VPN, all your raw data on the internet such as your personal data, voice or videos will be channelled through an encrypted and secure virtual tunnel between your device (computer, smartphone, tablet, etc.) and a VPN provider’s servers around the world.
Both HTTPS and VPNs work together to protect your Internet online. They go together like peanut butter and jelly to complement each other. Again, they are not direct substitutes for one another, but help you to keep yourself protected when surfing.
Relying on the encryption of HTTPS alone is not enough if you value your Internet security. It still leaves much vulnerabilities open. Hence, it is advisable to always use a VPN connection if you are surfing on HTTP or HTTPS websites for a more complete surfing experience.