I believe that it is all subjective in opinions regarding the type of computer that you use, whether it is Mac or Windows. I will just state my opinion why a MBP laptop is better than an HP laptop
1) Apple Retail Stores: Great service. I like having a place where I can go and get help on my Mac if it has any issues. My experience so far is that they are very attentive. It is going to be hard with HP as they are sold through 3rd party retailers or online.
2) Apple Service: As mentioned, it is very good (as long as the warranty still in place). With Applecare, your computer will be covered longer, but my MBP is 3 years old and is still going strong without Applecare so....
3) Multi-touch Trackpad: It is going to be hard to imagine going to a PC laptop after using the MBP trackpad. It is simply magical. Different productive gestures and very responsive. Once you use it, you can never go back to a PC touchpad. I'm sure it saves me a second or two here and there, but it all adds up, right?
4) Mac OSX: It is easy to use and intuitive. The moment you turn the computer on, it just works. There is no bloatware, and it is fast and fluid. All installations are very quick and easy. The program that you need are there (iLife and can pay extra for iWork)
5) Bootcamp: Best of both worlds. If you want to jump from OS X to Windows, it is easy. From Windows to OS X, it is a bit more difficult.
5) Aluminium(how Sir Jony would say it). The MBP is a beautiful machine. Aluminum unibody casing vs many plastic PCs. I'm sure that will ensure durability as well. There are new PC laptops come out with metal casing as well, but they are just as expensive, and they don't have OS X.
6) Apple Ecosystem. Some people like it, and some don't. However, it is working very well for me. I have many Apple products and they all sync effortlessly. iCloud is very nice to keep all things together. Airplay from a Mac to an Apple TV is pretty awesome as well.
I'm sure that I'm missing something, but someone will fill in.
**Disclaimer: I don't work for apple Just a guy who likes his Macs
Sorry about the long post as well. I am doing a long paper for school right now, and describing my experience of Mac computers is much more interesting