Explain the difference between the sandbox types and how you choose between them.

Four types, distinguished by what they copy and how often they can be refreshed.

• Developer — configuration only, small data allowance, shortest refresh interval. The default for individual development work.
• Developer Pro — configuration only, a larger data allowance than Developer, same short refresh interval. Useful when a developer or a small test needs more seeded data than Developer allows.
• Partial Copy — configuration plus a sample of production data selected by a sandbox template, with a per-object record cap, and a medium refresh interval. This is the workhorse for integration testing and limited UAT.
• Full — a complete copy of production configuration and data, with the longest refresh interval. The only option for performance and data-volume testing, and the most production-like environment for rehearsal.

I choose by asking two questions: how much data fidelity does the activity genuinely need, and how often does this environment have to be reset? The second question is what eliminates Full sandboxes from most roles — teams reach for Full because it is the most realistic, then discover the release calendar cannot wait for the refresh interval.

I always confirm the current storage limits and refresh intervals in Salesforce Help before writing them into a design, because the numbers are refined between releases and a design document that quotes them from memory ages badly.