Hydrogen is gaseous at normal temperatures. Both Kerosene and hydrogen are flammable, but being gaseous means that the resulting exothermic reaction will happen

Hydrogen is gaseous at normal temperatures. Both Kerosene and hydrogen are flammable, but being gaseous means that the resulting exothermic reaction will happen much faster and thus the energy will be released much more violently (think:explosion). Additionally, as you said, storing hydrogen densely enough means pressured containers, or extreme cooling (like for rockets).