One of Galileo's surviving telescopes from 1610 has an objective lens diameter of 51mm and FL ( focal length) of 1,330mm. The plano-concave eyepiece has a FL of -94mm. That eyepiece is, still, called Galilean: it gives an upright image ( not upside down) , like the binoculars. The maximum power of the telescope is 14. Compared to 8 power binoculars with 42mm objective lenses, that doesn't seem bad.

However, the focal ratio ( the diameter of the objective compared to the focal length, written as f/) of those binoculars is likely around around 4- that's typical. The Galileo 'scope is f/26. That means that the binoculars give a much bigger field of view, at 8x, and more clarity in dim light- so, say, looking out over a whole landscape in the evening. The Galileo 'scope at 14x will be good for small, bright things- like, stars, or planets. Hard to use for bird-watching. And that, interestingly, is still a divide in star-gazing. If you want to look at all of Jupiter's moons, you want a telescope. If you want to survey a big, dim patch of the night sky, hoping to spot a comet, you want some big "light bucket" binoculars.

Another thing the binoculars have and the Galileo 'scope doesn't is achromatic lenses. Simple glass lenses create an aberration in color. You have no doubt seen prisms produce a spectrum? That will happen with plain lenses- objects are given a rainbow halo. By combing two different kinds of lenses, of two different kinds of glass, that rainbow effect is eliminated- but achromatic objectives would not arrive until the 18th c.

There are other things, like precision focusers, sealed construction to keep lenses from fogging up in the rain, perhaps better light stops to keep down the glare within the tube...but I don't know those details on the Galileo 'scope . There's also the lens quality. The next century would see significant improvements in lens making ( Baruch Spinoza, for example, made his living making lenses, not philosophy) so, you suspect that Galileo's 'scopes would have small defects, less clear images- but, for looking at very small bright objects, perhaps that would not be such a big problem.