I recently posed this question the other way around, i.e. a site had different pages (technically totally unconnected) for each product variant and it caused certain problems: https://moz.com/community/q/duplicate-content-through-product-variants
I am not sure if this 100% applies to you: I would not use "different model" and "variant" as synonyms. If they are different models, they are different, unique products and have distinct features, advantages, maybe extras etc. Variants, to me, are for example different colour, maybe the same model with different extras or similar. There might be some grey zone where different models might actually be quite like variants, differing little from each other - then I'd ask if they differ enough to say something about each and/or contrast them.
For different models I would in fact chose different pages that go deeper into details. (Think of different books from the same publisher!) For variants, having more than one page is problematic. If I had the free choice, I'd bundle all variants on a single page with dropdowns to select the variant. There is also the question if variants are sufficiently different to write unique content for each - if that is the case, it could justify separate pages. A definite benefit of those is that they can be linked directly.
Regards,
Nico