No, all cookies are not the same, they can be different in purpose. Cookies are usually split into two separate groups:

• session cookies – these cookies are temporary and are erased when you close your browser after visiting a website. The next time you visit the same website it will not recognize you since session cookies don’t track information for optimization purposes.
• Persistent cookies – these cookies remain on your hard drive until you erase them or they expire. Such cookies are used to optimize the browsing experience for the visitor and to remember the actions a visitor has made while moving around in the website. Persistent cookies then can figure out what people like about the website to help improve the user experience. The most popular persistent cookie is a Google Analytics cookie - many websites worldwide use Google Analytics to track performance.