Have you read anything on PSVT? That's Paroxysmal Supraventricular Tachycardia. I have that and it's just as the name says - paroxysmal: an abrupt change in rate. Apparently it's pretty benign (I've had it for at least 50 years) but strange and uncomfortable. Never had VT but I would guess too many beats of VT and you'd pass out since the ventricles wouldn't be pumping all that well. Just a thought. Have you worn a Holter or event monitor?
What is the difference in the feelings between SVT and VT.
There is really no difference in the way they feel to you. you can't tell. If you don't have any history of heart disease, the probability of it being VT is very low.
Do you think this is a reason for concern or does it sound okay to you.
If you have been examined by a cardiologist and they aren't worried, you probably don't need to worry. I deal mostly with heart rhythms. When I have someone with concerns like yours I put on them on a 30 day monitor and wait to see a recording of what is causing your symptoms. It is really the only way to answer the question. If it happens several times per week it should be an easy thing to record.
I hope this helps and your welcome.