Hoping to get some Datejust II questions answered

[MitchellWiggs]

I currently have a stainless DJ 36 on a jubilee, and wanted to upgrade to something a bit bigger. I started looking into the larger styles, and really fell in love with the DJ on the left.

As I was researching, I see people talking about the DJ II and the DJ 41, as if they're different models, but I thought that the DJ II pictured is the 41? I think there's something I'm missing or am not understanding lol.

Also, I was wondering if anyone knew what the roman numerals are called when they're outlined in gold (pictured on the right) as opposed to the solid gold numerals (on the left)?

Could someone explain why there's a bar at the 9 o'clock marker on the one one the right, and why it isn't on the left? Sorry for all the questions, I just want to make sure I understand everything before I buy. Thanks guys.