An in-house team buys you the deepest product knowledge. The developers absorb your domain in a way no external team will match, and that knowledge stays with you. The catch comes in the form of time and rigidity: filling a senior role takes months, ramping up takes several more weeks, and the salary continues whether the roadmap is full or empty.
Project outsourcing implies the vendor owns delivery: it staff augmentation they staff the roles, the partner manages the plan, and they absorb the staffing risk. This fits well when the work is a defined project and your side has a decision maker with time for it. It works badly when there is no one to answer questions, since the provider is not able to guess what the business wants.
Hiring individual contractors is the middle option: you add engineers but keep responsibility for delivery yourself. It moves quickly — a suitable engineer is often available almost immediately — and it winds down as quickly as it ramped up. The condition is that your own leads have to have time for code review and planning. If that capacity is missing, you end up paying for hours, not results.
In practice, the models mix. One durable pattern holds the critical decisions and the core system with permanent staff, while an outside vendor takes on the parts that are bounded and specifiable. The rule holds: retain what differentiates you, and delegate what is well understood.
A few questions resolve most of these debates. Start here: is this software development for regulated industries the product itself, or hire angular developer a supporting tool? Second: for how long will you need this capacity — months or years? Third: who answers the phone at two in the morning when it breaks? Answer those honestly and the appropriate option is normally clear.