What does the Suspend button do that the Power Off button cannot do?

Which is better to use when shutting down for the night, Suspend or Power Off?

Personally, when I have finished a session I power off. That way my next session starts with a clean boot from scratch.

That is what I have been doing also and which I will continue to do for the same reason too. Thanks.

I do the same thing and shut down my computer overnight, unless I'm in the middle of my work and don't want to close everything so I can pick up right where I left off the next day.
I think it depends on personal preference. Some users only shut down their computers once a week or even less often.
When the computer is in sleep mode, it still uses power the whole time, whereas when it’s shut down, it doesn’t. However, frequent restarts can also damage the computer. Unfortunately, I don’t know what the best compromise is.
Personally, this is what I do: During the day, when I take a break, I put it to suspend, and at night, I shut it down.