I bought several VPSes across different VPS providers. Although I chose Ubuntu 20.04 on all providers, I found they use different Linux kernels. There might be other differences as well. In order to keep my running environment stable, I want to use the same OS image in all VPSes. But I think it’s impossible, it seems, that every vendor has some modification on internet options at least.
Some VPS will manage your kernel for you and use a ‘optimized’ kernel. You can often change it to what you want. But sometimes you have to go into the control panel to change it.