There's a big difference between the two:
The Cimex is a rotary cleaning machine that has a patented three-head mechanism, incorporating a counter rotating planetary system, which not only ensures a more thorough cleaning action, but also allows greater operational control with a torque-less action.
This three-head system makes the operator's task much easier as it eliminates the tendency to "slide" which can be encountered with a single head machine.
The Cimex has three x eight inch drive boards which holds a fibrous pad on each.
A beige colour (softer) pad, for normal cleaning, or a grey colour which is more coarser and gives about a 20% better clean.
The grey pads also wear down quicker.
I use this for nearly every one of my commercial carpet cleaning jobs, mostly with the beige pads.
The Orbot is a compact, versatile commercial and residential orbital floor machine.
The Orbot can use three different size drive boards: 17", 19", and 21".
You can also use an assortment of pads and brushes to clean, scrub, sand, strip, and polish any carpet and hard floor.
I now prefer to stick with carpets, in commercial I use the large fibrous pads, similar to the Cimex, but in 17" size.
If I'm doing residential, I will use the bonnets, of which there are several different types depending on how soiled the carpet is, or if you need to dry a carpet by using a bonnet that looks more like a mop.
I have only ever used the 17" and am happy with that.
I really love my Cimex, (which is made in the U.K.), and I found it very easy to use for a beginner, my wife watched me use it the first time, and as soon as I stopped, she jumped on and started using it.
That's confidence.
The Cimex is more suited to larger areas and you can really fly through those big jobs, also, I have put it into many tight areas where I could never put the Orbot.
The Cimex is heavier than the Orbot, but weight is distributed better.
I can also get further under office desks with the "Mex"; than I can with the Orbot, due to the solution tank placement and ease of releasing the handle to a lower angle.
The Orbot uses less solution and water than the Cimex over an equal amount of M2, but also has a solution tank that is about 1/3 the size of the Cimex, so you are stopping and filling a bit more often.
On large jobs, the Cimex runs for about one hour on average for me, before stopping to add more solution and water.
Compared to a truck mount, I use about 1/5 the amount of water using the Cimex, even less with the Orbot.
I've had the Cimex for in excess of eight years and the only problem was a cracked solution tank.
I also installed oversize wheels and pneumatic tyres on it which made a BIG difference.
Hope this helps and that I haven't broken any rules here on a comparison of my experiences with both machines.
Shorty.