Two different costs
A hire is a monthly cost that starts on day one and runs whether or not anything ships. A sprint is one price for one outcome. Before the hire writes a line of code, there is a search, interviews and onboarding, which usually takes three to six months for a senior engineer.
Where the difference shows
It shows in time and in risk. A sprint ships the first version in 2 to 12 weeks, and if the fit is wrong you can leave after week one with everything built. A hire is a long commitment that is hard to undo. It also shows in range: one person brings one set of skills, while a sprint brings in a specialist for the parts that need one.
When not to pick us
If the software is the core of your company, you need people who own it full time. A sprint can still build the first version, but plan the hire from the start.