What is a 'protocol upgrade'?

What does 'general software maintenance' mean, and why is this needed?

What is the difference?

Can someone use a metaphor or use child language to explain this to me and any other feeling ignorant on this subject?

And please assume that all I know about computers is how to turn them on & off.

#asknostr #bitcoin #protocol #OG #developers #devs #generalsoftwaremaintenance #bitcoinsoftware #core #node