Stephen Krashen has a monitor theory which contains five hypotheses. The first one; The acquisition-learning hypothesis states that acquisition is a subconscious process. You can compare it to the way a child learns its first language. By learning a language the process takes place in a conscious state of mind. You learn rules and grammar and Krashen says that learning cannot lead to acquisition.
The second hypothesis is the monitor hypothesis. It tells that the things we learn about a language can only be used as a monitor. What he means by that is that our knowledge about a language can be used to correct our own writing and speaking. But in a realistic conversation situation it's not likely that we have time to monitor our own speaking.
The natural order hypothesis tells that acquisition of grammatical structures comes in a predictable order. Some structures come early others late.
The input hypothesis speak of acquisition. Comprehensible input is very important. The learner must be exposed to input on an slightly higher level than he is presently at. This is a formula called i+1. The i stands for current level of competence and the 1 stands for a level just above the level of competence. The importance of comprehensible material is emphasized. The learner has to understand the meaning first, and then they acquire a new language. Fluency emerges over time if you are exposed to it on a right level and in right amount. Another important side of this hypothesis is the learners already existing knowledge. If a learner has knowledge of a topic it becomes more comprehensible.
The last hypothesis is the affective filter. It tells of the learners emotional state and that it can block or pass different input. The learner has to be motivated and have self-confidence to be able to really acquire something. If a learners affective filter is raised he won't learn anything. That is why it is so important to make the learners feel comfortable and don't make them do anything they're not ready for. By pushing people to do something they find scary you may rise their affective filter and they won't learn a thing.
So to summon it up; learning cannot lead to acquisition. Your knowledge can be used as an error controller but it won't make you speak a language more fluently. You can only improve your fluency by being exposed to a language over time and this is a subconscious process.
The reason why I'm writing this is to help me understand and remember. I know I'm summoning up the topics in the book. But by writing it down it's easier to sort out the differences in the topics. And things make more sense than if I just read it. So this is kind of my middle stage. I try to make reason out of these theories and print them into my mind.