Founders use these terms interchangeably, but they are different things.
The confusion is understandable. Both roles involve senior finance thinking. Both can be done on a fractional basis. And in practice, a strong person in either role will bleed into the other's territory. But the core scope is different, and that difference matters when you're deciding what to hire.
What a CFO actually covers
A CFO is the senior financial executive of the company. That means banking relationships, audit management, legal entity structure, board-level communication, and ultimate accountability for the financial health of the business. At a growth-stage company, it also means being a strategic partner to the CEO on major decisions, capital allocation, and company-wide planning.
The most valuable fractional CFOs bring FP&A skills, executive presence, and pattern recognition from having operated at a higher level across multiple companies. That combination is genuinely hard to find and commands a premium. You're paying for the reps, not just the hours.
What FP&A actually covers
FP&A is narrower in scope and more focused on planning and decision support. Building and maintaining financial models, running the budgeting and forecasting process, producing board reporting, and helping the business understand what's driving performance. The goal of FP&A is to help the company make better decisions, not to manage the full financial function.
If what you need is someone to own the planning process, keep the model current, and translate the numbers into something useful for leadership, fractional FP&A often covers it completely. You don't need CFO-level breadth for that job.
How to know which one you need
The clearest way to figure this out is to write down what you actually need done. If the list includes investor relations, banking, or board-level financial leadership, you probably need the CFO profile. If the list is model builds, budget cycles, variance analysis, and board prep support, fractional FP&A is likely enough and will cost less.
Most early-stage companies hire at the CFO level when they actually need FP&A coverage. They're pattern matching to what a "real" finance hire looks like without checking whether the scope justifies it.
The scope question is worth asking explicitly
A good fractional CFO should be honest with you about this. If you describe what you need and the scope is really FP&A work, they should tell you that. If they don't, that's worth noting.
The right hire is the one that matches what the job actually is, not the most impressive title you can afford. At Series A and B, that's usually fractional FP&A. By Series C and beyond, depending on what's on the horizon, the CFO profile starts to make more sense.