There are many types of systematic reviews. They may ask different kinds of questions and use a variety of methods, just like primary research. As with primary research, they vary in terms of perspective, purpose, approach, methods, and the time and resources used to conduct them.
Some reviews may ask broad questions (over a wide topic area) and examine them in little detail whilst others may ask narrow questions that are examined in great detail. Some reviews ask such broad questions that these are split into sub-questions that are addressed by different sub-components in the review each with different review methods considering different types of primary studies (multi-component reviews).