The real value of samādhi lies with wisdom. The difference between samādhi and wisdom is that samādhi renders the mind calm and undefiled for only a limited time. When the mind leaves that state of calm it experiences various sensations which proceed to influence the mind as before. Sensations which are the bases for greed, hatred and delusion arise once more. You see, the mind is still the same as before, except that when the mind enters samādhi it rests with a harmless sensation, so that defilements don't arise. As soon as the mind encounters harmful sensations once more, the defilements arise as before.
Therefore the results of simply practicing samādhi still leave us prone to problems. Suffering still arises, the disease is still with us. Samādhi in itself does not give us a real, lasting result. One who transcends the influence of defilements temporarily, by using samādhi, is said to have experienced vikkhambhana vimutti, transcendence through suppression. The illustration given is of covering grass with a rock. As long as the rock is there, the grass is suppressed and cannot grow, but once the rock is removed, the grass grows as before.
How can we cure the problem once and for all, so that, even when the mind experiences various sensations, no harm or problems arise? One must delve deeper into the problem, by destroying the seed of defilement in the mind, so that the mind does not react with defilement to the various sensations.
This is called abandoning the defilements through true knowledge and vision of the way things are, that is, by using wisdom. Wisdom on this level is called vipassanā.
Thus, when we talk of the higher levels of Buddhist practice, it is said to have two main branches. On one hand, samādhi in itself, which we call samatha, calm, and on the other hand, the use of wisdom, seeing the true nature of things, which is called vipassanā. If one develops samādhi and then uses that calm mind in the development of wisdom, one will achieve what in Buddhism we would consider to be comprehensive results.