What is the difference between chosen-plaintext attack and adaptive-chosen-plaintext attack? I've just dived in cryptography and would like to learn basics of this science.

Currently I can't understand the difference between these two types of attacks. As I understood from Bruce Schneier's book "Applied Cryptography", adaptive-chosen-plaintext attack is similar to chosen chosen-plaintext attack, but cryptanalyst can modify his choice (plaintext) based on previously got result.

What does this suppose to mean? In chosen-plaintext attack cryptanalyst also is choosing the plaintext. So what is the difference?
With chosen-plaintext attack, the attacker is allowed to choose an arbitary amount of plaintext to encrypt. After that he/she can't do that again, he/she has to work with the current data.

With the adaptive-chosen-plaintext attack, he/she can do the same as with the chosen-plaintext attack, but is also allowed to encrypt new data after the attacker has looked and analyzed previous encrypted bits. He/she can, based on the already encrypted data, choose new data to further advance his/her attack.