Is the boost offset machined into the cranks themselves or is it the chain ring which gives the increased chain line? i.e. are the cranks the same between boost and non-boost but just with a different ‘boost’ chain ring?

Different arms for the Shimano stuff.

It’s the cranks.

However, if you don’t need the extra 3mm for tyre or chainstay clearance then the non-Boost version will play fine with a Boost hub.

thanks for the replies, its chainstay clearance which is the issue but I have ended up fitting a 1mm spacer on the driveside BB to give a bit more clearance for now.