There's kind of two layers to how I think - if I'm actively thinking about something (such as writing this post, or imagine a specific event/occurrence), then it is a very defined internal monologue, and is essentially how I would speak about the topic.

If its a more passive thing (such as pondering something whilst actually working on something else), or my language 'skills' for lack of a better word are doing something else (e.g. listening to music with lyrics), then the thoughts are more abstract ideas and images, and the monologue only returns when I come to some sort of conclusion. It's interesting to note that this happens more frequently when I've been using languages other than English.

Brains definitely are weird.