When water approaches both of them, no reaction is seen in the first compound, but the second compound react readily with water.
In my notes, it is written that CH3 causes steric effect and also +I effect which decreases the positive charge on the adjacent (sp2-hybridised) carbon. Hence, the first compound doesn't react with water.
But in CF3, I know it causes lots of -I, which increases the positive charge on the adjacent carbon, but won't it also cause steric effect too? The lone pair on Fluorine and approaching oxygen of H2O shall hinder each other? (But it does react.)