In general, premise supports the conclusion. But that doesn't always mean premise is the reason why the conclusion is taking place. In cause and effect reasoning, it is implied that the premise causes the conclusion to happen. This may or may not be true.
For example-
In the last 20 years, there has been a significant increase in coffee consumption. During this same time period, there has been an increasing number of public coffee shops in urban areas. Therefore, the increase in the number of public coffee shops must have caused the increase in coffee consumption.
Here the conclusion implies a causal relationship, which may or may not be true. There might be some other reason for the increase in coffee consumption. However, the first part is always the premise and the part after therefore is always the conclusion.
Hope it helps