It seems there are some dreams that are extremely vivid and I can remember almost every detail about them, while there are other dreams that are broken and I can only remember pieces of them. Why exactly does this happen? Sorry if I seem a little vague on what I’m asking. If you don’t understand, just tell me
There might be two reasons…
it might be like with waking life memory-some things you remember better due to your character,your nature so on.Then some of them you will be able to wizualize better ,some worse.
Second reason might be just recall- you sometimes wake up straight from a dream and sometimes minutes after…that influences how you remember dreams.
take care:)
Also could be the sleep level (depth and stage) you had your dream in.
Thats mostly the case!
Also how many hours of sleep u had that night before u woke up etc.
Catch your dreams! 
jeff
Perhaps a whole other, more shamanic explanation:
Very vivid dreams are signs that the Dream Creator, whoever/whatever that is, wants to send us an important message, often about our health, emotional affairs, our job, … practically any waking life situation, even if they haven’t occured yet. The vividness of the dream is to make us realize the importance or necessity of the message.
Often the general vividness of our dreams seems to increase when we approach turning points in our lives, whether we realize it or not. In this sense, vivid dreams can be used as guides to lead us on the right track at the turning point. In this view, I don’t think it’s relevant to search for a scientific explanation of the increased vividness, because this would only veil the message and reduce it to a mixture of reacting chemicals coming from the brain stem.
In lucid dreams, you can often enhance the vividness, so it’s not always set in stone.
True, but I was mainly talking about the natural vividness of NDs. I say natural, because you can increase vividness also by the use of chemical supplements such as B6, melatonin,… In this sense, natural NDs can be a great source of wisdom, while LDs can be the perfect test laboratory for you to apply this gathered wisdom into waking life situations.