Off the top of my head...
From at least ~99' ARB resold the 35, 45 and 60 quart Engels under their own name, basically a different case color and labeling on the unit, other than that the exact same specs, parts and of course the Sawafuji swing motor that has been such a proven unit. In ~05' ARB discontinued their 35 and 60 units and focused on the new 45 unit which then included a built in LCD thermometer located right next to the control switch on the back of the unit, other than that it was identical to the standard Engel. Engel themselves did not offer this thermo equipped unit in the US, only the ARB unit however Engel did continue to offer the 35 & 60 as well as their other sizing options. ARB did have their own Transit Bag which differed from the Engel unit quite a bit and has actually been a favorite amongst many including Engel branded units. In 2009 ARB released their solo branded unit, featuring the same Danfoss motor used in various freezer/fridge units (National Luna, Waeco, etc). So if you have an ARB other than the newest unit, then its an Sawafugi/Engel and spares, etc can be ordered from any Engel dealer. If you unit is less than 6 months old, chances are you have the new unit unless you stumbled across some 'new old stock'.
Plent of reviews of each here on the forum.