Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
I work as manager in Apple authorised service centre UK, and this is directly copied from GSX article on servicing the Apple watch, does not mention other bands.

AC+ Coverage

1) AppleCare+ (AC+) covers Apple Watch and all in-box accessories.

That is all... The people you all talk to on the phone and also the "genius" guys are only people who are knowledgable in Apple products, they do not service them, they haven't a clue most of the time with technical questions ��

This might of course explain why the model number, visible in Settings, General, About says a specific model that has a bracelet combination. e.g. mine whows as a MJ3X2B/A which reveals it as a 42mm SS with Black Classic Buckle.

I wondered why they might go as far as making the model number specific to the band on the watch body.
 
This might of course explain why the model number, visible in Settings, General, About says a specific model that has a bracelet combination. e.g. mine whows as a MJ3X2B/A which reveals it as a 42mm SS with Black Classic Buckle.

I wondered why they might go as far as making the model number specific to the band on the watch body.

That's exactly why, so we know what band belongs to the body.
 
I certainly think that if the info provided to the OP Were true Apple would have made the connections incompatible with each other. I.e. A SS model band would simply not fit a Sport Watch and vice-versa.
 
Obviously the design of the watches are exactly the same, just different materials used.

The band will fit each one the same, just the aluminium is softer than steel, so you can expect some degrading from the body if it's attached and reattached over months, but I'm guessing people won't be changing the straps too much for there to be any major difference.

Only issue which may arise is if it did make the connection loose using a steel end in a aluminium body, it may void warranty, in this sense they are not compatible if you would like to have no issues with warranty, but that is all.
 
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.