Bifocal lenses allow for one set of eyewear that corrects both nearsightedness and presbyopia. Varifocal lenses also combine distance and reading prescriptions into one lens, but the transition between prescriptions is seamless, meaning there is no line in the lenses. They also correct blurry vision in the intermediate range. Unlike bifocals, varifocal lenses do not have a seam where the two prescriptions meet. They also allow for correction of mid-range or arm's-length vision. However, due to the way the lenses are made, varifocals create some distortion.
Bifocal lenses have two different areas that is used to correct both nearsightedness and presbyopia. And a line is visible in the bifocal lens.While varifocal lenses do not have a line where the two prescriptions meet and can correct the vision for mid-range or arm's-length , so you can use varifocal glasses to see computer.