It's similar in terms of what signals come out of each pin but differ electrically. As Atro said, the genny2 scart cable has the cap and resistor combo in the cable while in the omega those parts are in the system. It'll work but result in a darker picture. What I normally tell people is that if you're in a pinch, you can use a genny2 composite stereo cable as those sets of pins are unmodified compared to a genny2. The remaining pins were modified in some form to accommodate s-video and component output.
The hdretrovision cable won't work with the omega since the cable needs +5v to operate while the omega puts out +12v to ensure that 4:3 aspect ratio is enabled by default on scart televisions. The omega also natively outputs component so all you would need is the cable that bubz linked to.