Self-reflection is important metacognitive skill, enabling students to build coherence into their learning and embed content in a broader context. While various pedagogical techniques exist to encourage student reflection, little research has examined the differences between formally guided, partially guided and unguided reflections. This study focuses on student responses to online Guided Reflection Forms (GRFs) from students in a first-semester non-physics class and, separately, a sophomore-level Vibrations & Waves course for physics majors, and compares these guided reflections with partially guided and unguided journals from a STEM enrichment summer program for incoming college students. A previously developed coding scheme was used on guided reflections and the LIWC computational linguistics tool used to confirm the distinct nature of the categories. A new coding scheme was created and validated for the unguided journals. We find that both guided and unguided reflections elicit metacognitive and reflective practice, although of measurably different frequencies and kinds.