Hi... yes it is the same thing...

they both seem of the same meaning and effect. only that to me, to "get inside" is rather a 'command' compared to "go inside" which is just a slight suggestion. :)

For me, "Let's get inside" gives me the feeling that the people need to get away from someone or something, like the rain, or maybe someone they don't want to talk to. "Let's go inside" just seems like a suggestion to go inside, for whatever reason.

They mean the exact same thing. It's just a different way of saying it

get emphisizes the effert of go inside.. For example: i know it's hard to go inside but let's get in it.( do you know what i mean)