What is the difference between DbContext.SaveChanges() and DbContext.SaveChangesAsync()?

SaveChanges() blocks the calling thread until the database finishes, while SaveChangesAsync() frees the thread while it waits. The async version returns a Task<int> that you await. Otherwise they do the same work. Both write the tracked changes in one transaction and return the number of entries written.

// Synchronous
int changesCount = context.SaveChanges();
// Asynchronous
changesCount = await context.SaveChangesAsync();

In a web app, a blocked thread cannot serve other requests, so async gives better scalability under high traffic. In a desktop app it keeps the UI responsive. Async does not make a single save faster.

Always await the call before you use the context again. EF Core does not support two operations running at the same time on one DbContext.