Ok, I'm not a complete moron,

but is the only difference between a "standard" app and a web app that it can send or receive data from/to the web?
I keep hearing about people suggesting them for a project I'm working on but have not been able to "view" one. Everyone that has recommended a web app to me has stated "you usually cant see them"

Not knowing exactly what these guys mean, either they guys are all trying to sell me the emperors new clothes, or it's hidden in something like the process a website takes to get information.
I'm sure it's probably as simple as a the way a bank website works but want to make sure. I'd hate to hire someone and have
a horrible project to present. (or be standing there naked

)
If I'm correct, a standard app is the basic grey box put data in and get data out type, while a web app could appear to be like a web page and can be used "on the net" as well as off.
Is this a good general description, or am I just staring at the walls lost?