Raised beds can warm earlier
More exposed sides and better drainage can make a raised bed dry faster than a deep border, especially in full sun. The effect depends on the bed height, soil mix, and how established the roots are.
Open ground has a bigger water reserve
Plants in the ground can often reach deeper moisture, particularly once their roots are established. Heavy clay may hold water for longer, while sandy soil can lose it quickly.
The best comparison is your own soil
Dig or feel a small distance below the surface in each planting area. Watering the surface until it looks wet is not the same as recharging the root zone.