Hard and Soft are informal classifications to martial arts styles. All martial arts will teach through repitition, practice, and study, but between hard and soft are some philosophical and practical differences.

Hard martial arts deal with linear, direct techniques where force is met with force. A block in a hard style can be seen as an attack on the opponent's kick or punch. Karate, kung fu, muay thai, and tae kwon do are all popular and well-known examples of Hard-style martial arts. In the martial art that I practice, I take inspiration from eskrima, a Filipino weapons form in which the basic set of strikes are also the basic set of blocks. Qin Na is an excellent example of the progression in the refinement and precision that can be achieved within this framework.

Soft style martial arts seek to redirect force and upset balance. The opponent's energy and attack vectors are taken and manipulated into elegantly upsetting the attacker's equilibrium. The end result is an opponent whose own momentum is used against them (in a throw or trip) or who is brought into compromising holds and chokes. Examples of soft styles include aikido, some kung fu styles, jiu-jitsu, ninjitsu, and tai chi.

Could either style be considered better, or more effective? Of course, it depends on how you measure it. YMMV, depending on the personal philosophy you already hold, and how well it matches up with that of the school's you choose. Soft styles will tend to have a more gentle and pacifist mentality, and Hard styles will have the complementing overt and sport related competitive feel.

In the end, if you are serious about martial arts, you should probably study both.