Aspect is a grammatical notion, and refers to the way in which the unfolding of situations over time is encoded in language, typically through the use of grammatical patterns involving auxiliary verbs. For example, They are discussing it uses progressive aspect and presents the action as ongoing.
Some grammarians refer to the perfect construction as 'perfect aspect', as in They have discussed it, which indicates that the action occurred before the present, but has relevance in the present. Other grammarians refer to perfect constructions as 'perfect tense'. The National Curriculum refers to 'perfect tense' rather than 'perfect aspect', and it is reasonable for teachers to follow that usage.