First off, let's clear up the difference between aftershave, eau de toilette, and cologne – it's a common misconception that the terms are interchangeable.
It's all to do with strength. An aftershave is the weakest, and is made up of around 1%-3% perfume oil. To help soothe your skin after a shave, it'll usually contain soothing and cooling ingredients, such as Aloe Vera. It should only last around two to three hours after application.
An eau de toilette (EDT) is made up of around 4%-8% of perfume oil. This is too much oil to apply to the face, so should be put on the 'pulse points' (neck, wrist, or chest). It should last around six to eight hours after application.
A cologne contains between 2%-5% oil, and is a happy medium between aftershave and EDT.
Finally, if you're looking for something really powerful, a parfum or perfume contains around 15%-30% oil. That means you only need a tiny amount on the pulse points to last for a long time. It is quite rare and expensive.