No, the ODYSSEY is NOT a gel cell. It is an absorbed electrolyte type battery, meaning that there is no free acid inside the battery; all of the acid is kept absorbed in the glass mat separators. These separators serve to keep the positive and negative plates apart.
The key difference between the gel cell and the absorbed glass mat (AGM) cell lies in the fact that in the AGM cell all of the electrolyte is in the separator, whereas in the gel cell the acid is within the cells in a gel form. In fact, if the ODYSSEY battery were to split open, there would be no acid spillage!