Q: my new pro has more memory than the old one however it will not back up from my time machine as there isn't enough room on the new pro - Strange?

"Memory" (i.e. RAM) is different from "disk storage". You may be confusing the two.

Go to Apple > About This Mac > More Info > Storage

1. What is the size of your new MBP's disk storage? 256 GB? 512 GB?

2. How much is it using/how much is free?

Are you trying to back up your new MBP to your TM drive, or restore your old data FROM the TM back to the MBP?

How large is your hard drive?

And how much empty space is available?

Since you haven't set it up, what are the specs on the new one? How big is the hard drive?

And, since you said it won't accept Time Machine, exactly what steps have you gone through and at which point did it/you stop? And post the error message please.