Sadly, most ISP will say 'speeds up to xx mb', which can mean anything/nothing. They will rarely guarantee rated speeds. In addition most ISP will have you in a batch with other users. It's called contention ratio. So you could be splitting your connection with maybe up to 8 other users. Typically the contention ratio is 8:1. That can have an impact.
Then, 100%, USAFRet is asking the right initial question. Wireless/Wired have big differences. An example being my own connection. I've got 100mb up/20mb down. However, even at the best of times I only get 70mb down speeds - that's wired. I am on a 1:1 ratio though so that helps me. But wireless the speeds fluctuate like mad. Specially when distance is involved. The closer you are to the router (wireless) the better the signal and speeds. The further away the worse it gets. Your router may be new enough to have standard wireless and the 5G band too .ie Dual Band router. In smaller spaces the 5G connection can give great high speed and sustained connection. But the downside is it's shorter range. The standard 2g will give greater range, but less speeds. So that's something to consider.
With all of that said, make sure your PC/Laptop has the most up to date drivers for the system, specially wireless adaptors and the motherboard drivers for the ethernet controller.