Two pricing models for Azure SQL Database: DTU (Database Transaction Unit) bundles CPU, memory, and I/O into a simplified unit with fixed tiers; vCore lets you scale compute and storage independently and apply Reserved Capacity or Azure Hybrid Benefit discounts.
On AZ-305 the expected answer is almost always vCore, for its flexibility and compatibility with Hybrid Benefit (reusing on-premises SQL Server licenses). The Hyperscale tier (within vCore) is for databases that need to scale beyond 4 TB.
DTU vs. vCore purchasing model (Azure SQL) is a concept that can show up on the exam. Check the full guide to see it in context.