Stent restenosis means the area of the stent has some blockage usually due to clots. Drug eluding stents (DES) help prevent that condition from happening...usually aspirin and plavix regimen helps prevent as well, but restenosis happens in about 3% of the interventions within a year, and there can be associated pain (angina).
Occlusion means there is blockage of vessels that may cause pain due to a plaque buildup or clot.