I own and use both.
The difference could be compared to actually driving a car and playing a video game. You may get the same result - travel from point A to point B - whether actual or virtual - but you did it nonetheless.
Real world applications are live and recording music.
Playing live tube amps are heavy - sometimes tempermental - and heavy.
I like using tube amps live because in my opinion the experience physical and aurally is second to none. Moving air - tonality - playability - all come as part of the package with a tube amp.
I use an older elevenRack live - I use in ears for monitoring - my rack setup in small and light - FX built in - small rack, midi pedal and a few cables and I am ready to go.
If you listen thru in ears to a tube amp in another room mic-ed up there is little difference in your overall tonality as long as you have taken the time to dial the virtual machine in correctly.
Recording guitar using virtual amps or live amps can depend on your desired outcome. Most guitar sounds in rock, country, pop and most commercials recorded over the last 10 years or so have been modeled amps - no live amps - and there are rock records that have ElevenRack, line 6, Kemper and other virtual amp devices on the entire album - and major touring racks nowadays are outfitted with AxeFX and Kemper - among others.
Tube amps are LOUD - and really need to be turned up to get a good tonality from them. Virtual amps sound great out of the box most of the time.
Purchase both and see which direction you prefer to go. There are advantages and disadvantages with both depending on the situation - this is something that would be hard to choose one over the other all the time I suppose - but your mileage may vary.
Rent a rehearsal studio for a day and rent lots of tube amps and rent some amp modeler hardware as well and spend the day literally playing thru everything and making comparisons between them all - then you may be able to make an educated decision based on your new found experience.