Both are longer and more realistic yaoi about friends who become lovers. There is some time progression in both so you get to see the development of the relationship. Both have some heartwarming moments. However COMPLEX is definetly more, well complex.
Both are exceptionally well made manga about two long friends whose relationship changes from a deep friendship to romance. They go against the grain, being yaoi with a realistic slant and depth. Not only is the romantic element important as there is a focus on daily life and professional achievements.
These are subtle romance stories between males handled in such a way as to avoid yaoi clichés. Rules and Dear Green offer believable casts in real life situations with an emphasis on character development. Both are highly recommended.