What is the difference between a battery tester and a load tester?

Can you explain the key differences between a battery tester and a load tester? Are they used for similar purposes, or do they serve distinct functions in testing? I'm particularly interested in understanding how their testing methodologies and capabilities differ, and what types of applications or scenarios would warrant the use of one over the other. Additionally, if there are any specific features or advantages that one tester has over the other, I'd love to hear about those as well.