What is the difference between "cessation" and "nirodha"? How would it be experienced during meditation?
The between cessation and nirodha is "cessation" is an English word and "nirodha" is a Pali word that often does not literally mean "cessation" although often it does.
In meditation, the important "cessations" to be experienced are:
Cessation of craving.
Cessation of attachment.
Cessation of I-making & my-making.
Cessation of suffering.
Cessation of ignorance.
Cessation of ego-birthing, ego-aging & ego-dying.
In summary, all of the above "cessations" amount to the cessation of suffering (dukkha-nirodha).
Therefore, often, when the Pali teachings refer to "consciousness-nirodha"; "nama-rupa-nirodha"; "sense-contact-nirodha" and "feeling-nirodha"; what this means is consciousness, nama-rupa (mind-body), sense contact & feeling are no longer imprisoned by ignorance, craving, egoism & suffering.
Cessation can be experienced during meditation. And if cessation happens it is unmistakable. You just know that it happened.
Sometimes just one or a couple of senses/sense perceptions seem to be missing, no longer there. Just for a split second. For instance the perception/sense of smell can suddenly drop/cease. Full blown cessation would be if every one of the six senses drops/ceases simultaneously. In that case you will only know when you are back, so to speak, that cessation happened.
In any case, you will know it. It can't be missed because it has too much impact.
In Satipatthana, your job is to breath while calming your body and mind. As you do that, you don't think about the world, your life, your problems etc. - you only think about your immediate phenomenological environment: thoughts, feelings, broodings, pyschosomatic sensations etc. - in a sort-of detached impersonal "scientific" manner.
Nirodha is stopping and non-arising of asavas. Asavas are self-centric action impulses like "OMG I want to get this thing" or "OMG I want to get rid of this thing" etc. The "scientific" perspective of Satipatthana combined with breathing and calming leads to letting go of asavas, stopping of reifications (I-making and object-making) and settling down in peace.
The end result feels like Peace which is not-unconscious, but can't be characterized using any specific characterization. It is completely free from egoistic action impulses and ego-centric judgements. It is free from all reifications. It is free from any sense of conflict. It is suchness.