I am not an OT ninja yet, but some thoughts from my experiences:
The OT doesn’t have pendulum, euclidean or random sequencer stuff. You can only play back the sequencer tracks from start to finish (unless using song mode, which gives abit more flexibility). Also, unlike the rytm, trig conditions are not supported, although there is a way to abuse the LFOs for creating something resembling trig probability.
Unlike kits on the AR, the OT has up to four parts per pattern bank. This means that you can only have up to four different midi channel / program change settings per one OT bank. If you do not use pgm changes, this will not be a big issue to you, but it’s important to know this as it also limitss what you can pull off on the sampler side.
Now with all that out of the way, there is plenty awesome on the OT sequencer. You can lock midi notes to any major or minor scale, and use the 3 LFOs per track for modulating any midi seq related parameters (outside of midi ch & pgm chng settings). every sequencer track can have it’s own step lenght (up to 64) and clock division setting, so polymetry is well supported. Every track also has it’s own shuffle strenght and shuffle step track, so you can also have negative shuffle as well as esoteric shuffles that only apply to the trig steps of your choice.
Reload pattern is unfortunately not available, but instead you can copy the pattern into the pastebuffer for pasting back anytime, so kinda the same functionality. Rotating trig steps by fn + arrows works just like on the AR.
There’s note retrig, although it is not accessed like it is on the AR. Haven’t used this myself yet, You can also do retrigs with the arp.
There’s also an arpeggiator, which is brilliant for mangling around with some LFOs. You can create interesting note progressions by piling strategic LFO modulations to the arp settings. In addition to all the LFO settings on the AR, the OT also has an “LFO designer” where you can create a custom LFO shape, enabling very cool modulation tricks!
Every MIDI track has microtiming and up to 4 note chords per step (I don’t say polyphony because all the four notes must start and end at exactly the same time). You can also parameter lock midi CCs, but the definitions of the midi CC numbers at your disposal are tied to those 4 parts per pattern bank.
You can record into the MIDI tracks via a keyboard, but record quantization is only an on/off, affair, no fancy nondestructive adjustable quant strenght like on the AR.
The song mode has extra tricks up it’s sleeve. If you’ve ever used a tracker program on a computer, the same idea applies here as you can define subpattern ranges for repeats etc.
for 1/32nd note repeats (IIRC). For more control over the ratcheting speed, you’ll want to work with the arp as 
great