GraphQL has emerged as a popular choice for API development, offering flexibility and a focus on client data needs, but it also presents distinct differences and challenges compared to REST. While REST APIs leverage HTTP semantics with standardized methods and caching, GraphQL emphasizes customizable queries, mutations, and subscriptions, which can complicate operations like caching and error handling. Unlike REST, where error states are clearly defined by HTTP status codes, GraphQL can yield partial successes or failures, necessitating more intricate parsing of error responses. Security is another area where GraphQL and REST differ significantly; GraphQL's schema introspection and query complexity can introduce vulnerabilities such as potential DDoS attacks, which may be mitigated through techniques like rate-limiting and persisted queries. Despite these challenges, GraphQL offers advanced tooling and a strong community, making it a valuable asset for developers willing to navigate its unique landscape.