Similarity: for both plant S and T the time take for the blue cobalt chloride paper to turn pink for the upper surface of the leaf takes a longer time as compared to the the lower surface of the leaf.

Difference: the time take for the blue cobalt chloride paper to turn pink for plant S is shorter as compared to plant T

Two factors are the temperature and the humidity of the surrounding

Water moves up the plant stem through capillary action and through transpiration