Question

Can you tell why there is difference in heating of land and water

Answer 1

there is a difference in density.

Answer 2

Because the ocean water isn't moving into or through the atmosphere as a result of the sun's heating of the water, convection isn't the process influencing air and water temperature
difference. ... The heat of the ocean is being given off (radiated) into the air, thus making the air substantially warmer.

I hope it helps_