Yep, that Varta is exactly the same setup.....but the pack contains sulphuric acid as a liquid, not a gel. I'll have to take a pic of a REAL gel-cell by Yuasa that we have at work so you can see the difference. They can be mounted/operated/charged in ANY orientation. It's interesting that even Wikipedia seems confused about the differences between what a true gel-cell is and what a lead-acid battery is.
I think it might be a "misnomer" (sp?)
It's likely almost right in between acid and gel, design-wise. The reason I say that is that a lot of websites you look that battery up on has it under "gel" batteries. It's mostly I think because the stuff you put in is thicker than water. Not a "true" gel battery, but more a reference to the stuff you put in. I bet if the batteries were never supplied with the bottle ( pre-activated) that they wouldn 't have gotten the "wrong" name.
However, that said it IS still a "maintenance free" battery, which means that the OP's question of opening it and adding water would not really be "necessary" and I wonder how it would mix with that stuff from the bottle.
Wikipedia is only as good as the people putting the information in. A wiki allows anyone to submit information to it. However, there was a point in that article where they did mention that there were suggestions of merging that one into the lead acid definition.