Personal computers vary in specifications dependent on the person who is using the computer. Someone who runs lots of graphically intensive programs on their computer may want to invest more into a GPU and focus more on the visual aspects of their personal computer. On the other hand, there will be people that use their personal computers for smaller tasks that involve text editing and spreadsheet/database structuring, this on the other hand would involve lower system specs than usual meaning that this person doesn't need to put as much money into their computer system.
Personal computers are something that would be used when you are at home using the computer specifically for anything that could be deemed, 'personal use'. Most Personal Computers nowadays are used for things such as: event planning, flight booking, personal/business calculations, entertainment and various different e-commerce purposes.
With personal computers, anything is possible, it's your computer and you can do as you please with your personal system.
Mobile Computers have a unique set of specifications, this is because the device has to maintain handheld capabilities so parts for the device have to be small. However as technology advances we are able to get more and more advanced parts for handheld devices nowadays in smaller sizes.
Mobile computers are something that are used a lot nowadays. In our day and age its normal to see someone in public doing something some-what 'important' on their phone. Because technology is fast and inhuman it allows the possibility to have a running business that can minimise potential mistakes greatly.
Because technology has had this impact on society being able to do business related tasks on your phone, whilst on the move is something that allows efficient running of a company.