Learning to sing is no different than learning to play the guitar or the piano. It requires a great deal of discipline and practise to get your vocal cords working to the best of their ability. Copying other singers can be a good thing, but it can also be a bad thing. If you are not approaching the pitches correctly, or not using the appropriate mix of head and chest voice for the song, then it can be problem. This can create some very bad habits, and lead to hoarseness and possible damage.
Bottom line is, if it hurts or if you are straining for notes, then you are doing it wrong. Singing should feel easy and free. If you are grimacing and singing loudly during high notes then you are not singing freely.
Everyone’s vocal cords are different. That’s the fascinating thing about the vocal instrument. No two sound alike. Some voices are automatically pleasing, and some not so pleasing. Of course, this is all subjective. What’s pleasing to my ear may not be pleasing to your ear.
If you’re not sure how to make your singing better, then it’s a good idea to see a vocal coach with a reputable background to learn exercises that will help you build strength, endurance and better tone.