What's the difference between an iphone and a computer?

And not just: one has a keyboard, one doesn't, but like technically what makes an iphone or ipad not a computer? The ability to "compute", whatever that entails, vs the inability to compute?

An Iphone is a computer, it conforms to von neuman architecture. We just don't call it one because it is generally not cool to be a nerd or a geek

And an iPhone is less powerfull:
It has less ram and cpu is not as good because it's all really small.