What is the difference between cupcake and cake recipes? Is the a "best" way to alter them to be the opposite?

As far as I know, cake recipes need more fat/moisture because cakes have a longer baking time than cupcakes.
I don't fully understand your second question. You can make cupcakes out of a cake recipe but if you make a cake out of a cupcake recipe, it might be to dry.

Thanks, that's what I was looking for.

Actually I read it the other way around.

The smaller the cake pan, the more liquid you need. Therefore if you have a "cupcake" recipe it might be too moist in a cake pan.

Seriously, I have stopped looking at a recipe as a cake or cupcake recipe. The only problem I have found is if the weight of the sugar is too high over the weight of the flour, you will get a sunken cupcake instead of a flat or domed one. Underbaking will produce a sunken cupcake also.

Some recipes don't taste good as cupcakes, but the same recipe I tried didn't taste good to ME as a cake either. Notice I emphasized me. Everybody's taste is different when it comes to cake.

Now the method you use to mix the batter will produce a different cake and cupcake too. The two-stage method produces a different cake texture than the creaming method. As a result how it feels on the tongue will affect if it tastes moist or not and other things people look for in a cake.

I know there are cupcakes books out there with "cupcake" recipes, but I doubt they are truly just for cupcakes. What they are are different ratios of flour to the other ingredients and method of mixing the batter. Those two things will affect what a cake or cupcake tastes and look like irregardless if it says cupcake recipe or cake recipe.

I swear, I never heard of a recipe being for one or the other. This just seems to have come up since (some brand) brought out their "Cupcake Cake Mix" that yields half the cake for twice the price.

I know my gramma never had 2 different recipes. It was all cake.

indydebi I so agree with you !

I have bake my whole life with many recipes and I have never had a problem putting cake batter in a cupcake. Just watch for doneness.

I just use the same recipes for cake and cupcakes.

Reminds me of a customer asking "can you make Wedding Cupcakes"?

Yes, i make cupcakes and how you wish them to be decorated for your wedding will turn them into Wedding Cupcakes.

Oh, i thought Wedding Cupcakes were different to Birthday Cupcakes the customer said.

Customer got her Vanilla Wedding Cupcakes - and one week later her sister ordered the exact same cupcakes for her sons 2nd birthday.
4 weeks later i used that same recipe for the Mothers 51st Birthday Cake

I like to think that they never had baked - thus didn't honestly know.

Bluehue.