A fractional CMO is a part-time senior marketing executive who owns strategy, leads your internal team, and is accountable for business outcomes. A marketing agency is an external vendor that executes specific marketing functions (content, SEO, paid ads) under your direction. For B2B SaaS and growth-stage companies, the core difference is ownership: a fractional CMO owns the marketing strategy and is measured on pipeline and revenue. An agency owns deliverables and is measure