well if it's not a guitar song then it's not a problem, apart from getting a female singer.
A sampled guitar. Hmm how to explain. In the early days of recording there was simply real giutar as an option. Then along came synthesizers. Then you could record a series of notes and use midi to trigger different sounds, some only tried to be synth sounds, others to emulate a real instrument such as a string section, or piano, or a guitar, or drums. In general these synth versions of real instruments were pretty primitive and could be spotted a mile away. Then along came samplers. A sampler used short recordings called "samples" to try and recreate something more like the sintrument that had been sampled... For instruments like drums they were pretty good, but still able to be spotted. For a guitar they were still pretty far away from the real instrument sound.
Many VST instruments emulating real instruments are sample based, though some do use some pretty sophisticated physical modelling on top of the samples, yet to a trained ear they can still be spotted fairly easily. 999/1000 you can still spot that it is synth based. For some styles of music that is less of an issue.
The great thing about digitally created music is that it is clean and crisp and clear. For more complicated instruments like guitar you are more likely to get the sound you want with the real instrument. Piano is a different deal. It is a simpler instrument because the strings can be played in different ways, the notes can be bent to new pitches etc. There are apps that are pretty good for getting guitar, but yet again a trained ear or semi-trained ear can simply spot what app made it.
I hope that helps some more