So I think I’ve attached a couple of diagrams - very basic, I apologise.
Basically, a bifocal has 2 prescriptions in 1 lense. The distance prescription is in the top part of the lense, and the reading is in the (generally) D shaped segment at the bottom. You just flick your eyes down to read.
Varifocals have 3 prescriptions in one lense. Distance at the top, intermediate for things like computer work, and reading at the bottom. On a varifocal lense, there are no obvious markings like there are on a bifocal.
As a pp mentioned, it can take a few weeks to get used to varifocals. This tends to be because of the ‘soft focus’ (blurring) towards the sides of the lense. Essentially, this is where the three prescriptions are merging together, and you’re left with a corridor of clear focus. The more you pay for you varifocal lenses, the better quality it is, and the less blurring you have - your corridor of clear focus becomes wider.
The thing with varifocals is that you almost have to train yourself to use them. If you don’t wear varifocals, and need to look to your left, you can flick your eyes over and see it clearly. Not if you’re in varifocals. Because of the blurring, you have to move your head towards what you want to look at, so you can look through the clear part of the lense.
People can find this particularly annoying when driving.
Some people can also struggle with using stairs in both bifocals and varifocals. If you just move your eyes downwards, you look through the reading prescription and so the step seems closer than it is.
Generally, the advice (especially for Varis) is to persevere, but most opticians should have no issues with refunding you if you can’t get on with your glasses.
Sorry that was so long! In a former life, I worked in an opticians