Hi @martinm- welcome!, @dougcollins - hi , @HAWK - thanks for the heads up!
I need some background on the end user.
"Is it best practise to try and match up the primary navigation on both platforms"
What are the primary tasks on both platforms, will they be different?
"and have them redirect between"
Who will be using the platforms? Are the roles the same on both? Or are they different?
"is it best practise to try and match up the primary navigation on both platforms"
Depends on the information architecture you want to create for whom it will be serving - on each platform.
I agree with @dougcollins on standarzing navigation. Sometime though on large platforms where the cms is being used by editorial staff, the look and feel will be totally different from the main site, because it has to accommodate 3rd party enterprise design that comes out of the box, that doesn't have a budget to be maintained.
Let me know how it goes!