So according to Merriam Webster bread is:
a usually baked and leavened food made of a mixture whose basic constituent is flour or meal
And cake is:
A: a breadlike food made from a dough or batter that is usually fried or baked in small flat shapes and is often unleavened
B: a sweet baked food made from a dough or thick batter usually containing flour and sugar and often shortening, eggs, and a raising agent (such as baking powder)
And yet some people don't think that cake is bread.
As a general rule, I would see in a majority of cases that in a bread, gluten development is encouraged to provide a chewy texture. In a cake, you want to avoid gluten development to have a light and fluffy texture.
Special bread flours have high gluten content and cake flours have lower gluten for that reason.
Now we of course do have many exceptions, such as banana bread is low gluten and very sweet, while many biscuit recipes call for cake flour, but no one would call a biscuit a cake. In both those cases, I don't think you would like a banana bread or biscuit that has the strong gluten structure that a proper baguette has.
Cakes (especially something like donuts) can be yeast risen, and some breads like matzo or tortillas have no leavening, or breads can use chemical leavening like Irish soda bread.
I don't know if I've ever had GF bread, so I had to look up how it's made. I wondered how the bread would have the proper structure to rise without a gluten matrix, and it seems I was on to something. Reading up on it a bit, gums and starches are used to replace the function of the missing gluten. So while GF bread has no gluten, it's still made with a gluten replacement, and the same function is required for proper results.
If we change my qualifier to bread typically having a deliberately developed structural matrix with high elasticity, it covers wheat and GF breads. It still is fairly universal we want chewy breads and non-chewy cakes.