There are a lot of similar case designs and it's hard to tell from those photos, which it is. The best and most accurate way to determine the reference is to open the back. https://www.omegawatches.com/vintage-watches?product_collection=3177&v_watches_movement=2779
Hello and welcome here. Probably has a Cal. 1450. The Caseback is a press-in, those can be opened quite easily. The buckle is to early for this watch, probably even a fake. I don't know how much you paid. But often a vintage Omega Geneve can be had for a good deal, if you are searching for an inexpensive entry into Mechanical Watches from Omega.
Serial number: 54270175 Article ref: 74021112 Quartz Cal. 1378 (later replaced by 1478). Case number is 055DA1953378 - stainless and 18k gold case. Cheers, Al
Some of the Omegas you have shown might be women’s watches. If you think you might be bidding on one (or more) of them, ask about the sizes of those watches before you get involved.
This is true unless Archer shows up with his bag of tricks and does a serial number search. Then he can tell you exactly what you have.
If you want to learn about Constellations a great place to start is this blog http://omega-constellation-collectors.blogspot.com/?m=1 My Pie Pan says hello!