They are different paths, not opposite outcomes
A claim is a request for payment or another resolution, often made to an insurer. A lawsuit asks a court to resolve a civil dispute. A lawyer may pursue negotiations before or during litigation, and filing a lawsuit does not mean a trial is inevitable.
A lawsuit adds formal procedure
Court filing, service, pleadings, discovery, motions, and scheduling rules may apply. The exact procedure depends on the court and jurisdiction. The federal court overview linked below is illustrative; many injury disputes are governed by state law and state-court procedure.
Timing is a legal question
Negotiations do not necessarily pause a filing deadline. Notice rules, limitation periods, the identity of the parties, and the place of injury can affect timing. Ask a qualified lawyer to identify the applicable deadlines from the facts rather than relying on a general guide.
Questions to ask a lawyer
Ask which claim or claims may exist, who the potentially responsible parties and insurers are, what evidence should be preserved, what deadline analysis is required, and what facts might make litigation appropriate.