An app for mobile devices differs from traditional applications both for the support with which it is used and for the concept it contains. This is in effect an application software that is very similar to a generic application, but which is generally characterized by a simplification and elimination of the not strictly necessary, in order to obtain lightness, essentiality and speed, in line with the limited hardware resources of mobile devices compared to desktop computers, this means that the features of the app are very limited because very focused on a certain function. The name itself, in itself an abbreviation, can be perceived as a simplification of the full name "application" to give the idea of something simple and small. Apps are subdivided into native apps and web apps, with intermediate or mixed cases that are sometimes referred to as hybrid apps.
source wikipedia