What is the difference between SaaS and perpetual license ERP?

SaaS (Software as a Service) ERP charges a recurring subscription (monthly or annual), includes hosting and updates, and has lower upfront cost. Perpetual license ERP is a one-time software purchase you own forever, typically paired with annual maintenance fees (15-20% of license cost) and often requires self-hosted infrastructure. Most modern ERP vendors have moved to SaaS-only pricing.