Creatine is a supplement that once you start, you are meant to take it daily until you are done with using it even if you arent going to the gym everyday because you will lose saturation in your bloodstream. Creatine naturally occurs in meats and, in muscles, it converts ADP into ATP which is muscle fuel. This will allow you to perform more repetitions and the effects are most prominent in sets lasting 30-150 seconds. Its effects can also depend on how well you respond to it (i.e. it could give you 10 more reps and your friend 1 more). Also, with creatine, it takes a few weeks to become fully saturated in your bloodstream. You can make it take half as long by taking double the recommended dose for a week but it would be a waste to do it for any longer.
Pre-workout is a supplement that, as the name states, you take before you work out. The actual contents of the supplement vary from brand to brand, but generally, they have some kind of stimulator which is caffeine 99% of the time. The other ingredients that they have are what really changes from brand to brand and in a stim free pre-workout this will be all that they have in them. These ingredients typically are things to improve clarity of the mind, focus, hydration, and muscle pumps. I personally use gorilla mode and it allows me to really push myself and ignore the pain for another couple reps. This is really helpful for things like squats where going to true muscular failure can be exceedingly difficult due to the large amount of oxygen those muscles require.
