I certainly know how the two seem very different. Though I've never had video sessions, other meetings I've done a lot via video the last few years. I think it holds true for those instances as well, in therapy maybe it's a bit more "enhanced".

The best explanation I've come up with so far is it's somehow the "sum of all parts" that makes it different. Video usually is much closer to the persons face, you do not see the whole body. This not only changes the perspective of the face, but also what you can focus on. You can't see the shoes of your T unless the shoes somehow get brought up and T decides to show them. You can't see the whole room unless it's shown to you. You don't see the entry to the house, the flowers outside, the new roll of toilet paper in the bathroom. It's small things, but I think it adds up to a whole package. Not that I judge my T about the house he has his office in much, but it's gives you a different feeling. This all falls away for video conferences, no matter with what person.

There is a disconnect that happens when you don't experience the same surroundings.
When I see friends on video, it's them enjoying their cup of coffee from their mug, me the same with mine, we can't smell each others coffee. You can't comment on the coffee flavor. If your friend drops the mug, you can't help cleaning up or interact in any way besides commenting on it. On top of that, physical cues are much harder to read. You can't see them crossing their fingers to the point of their knuckles showing, or them whipping their leg, or anything... it's still possible to read the emotions, but it's much harder for me. And since I pick up on a lot, that bothers me to some extend.

For me, it creates kind of an impression of being in two different realities. You do experience some of the same things, i.e. the conversation, the topics, the video stream. But everything outside of it is not shared. This is of course also true for in person, but much less so. You have the same smells (not as in the same kind of smell, but literally the same smell from the same bottle of essential oil coming from the same place in the room), the same outside sounds, the same kind of acoustics, same time of day... I often struggle with the topics around my T and other people having their own reality, even though we share some parts. Video kind of enhances that feeling. A similar thing for me from therapy (though it's much, much less severe for video) is dissociation? You are there, with the person, on the video. But you're not there in all the ways that could be.

I, also, think it's kind of a personal preference. There are advantages to being able to connect from whatever place to whoever you want. Some people can deal with having separate realities from somebody else relatively well. Others like me struggle more with it, and then you might prefer in-person sessions.