Aspects
Aspects form when two planets are a certain number of degrees apart from each other. Depending on their distance apart, aspects signify certain things about the relationship between the two planets and indicate whether they will generally have beneficial or challenging effects.
Trines
Trines form when two planets are about 120 degrees apart from each other (depending on the orb used). The two planets generally exist in signs of the same modality in this aspect.
Trines are generally positive aspects that make life easier on a person. The energies of the two planets work cooperatively without getting in each others ways. Often trines indicate areas where we have talents or abilities that come naturally to us. It doesn't take much work at all to be rewarded by these aspects. However, if a person has too many trines (or other positive aspects) at work in their chart, it can have the effect of diminishing their need to work hard for things and as a result, laziness and other negative characteristics can develop as a result.
The Aspects