What is the difference between par and reorder point?

Par level and reorder point answer different questions: par is 'how much should I have?' — a target level you top stock up to on a schedule (order quantity = par minus what's on hand, so it varies each time). Reorder point is 'when should I order?' — a trigger level that fires whenever stock falls to it, usually ordering a fixed or calculated quantity.

Par levels rule hospitality and healthcare: bars, kitchens and clinics restock to par daily or weekly because consumption is steady and checks are routine. Reorder points rule retail, ecommerce and wholesale: demand varies by SKU, so each product carries its own trigger based on its sales rate and supplier lead time.

They can coexist (par for consumables, ROP for sellable stock). If demand swings or lead times are long, reorder points model reality better than a fixed par ever will.