What are three of the differing aspects in which disagreement occurs, and which some scholars consider to be what is meant by the Seven Ahruf?

Scholars have differed on the meaning of the seven ahruf (readings) with 35 different opinions. Among the aspects I have contemplated regarding the facets of qira'at (recitation) variations, I found seven, and among the reasons for these variations are: a change in vocalization while the meaning and form remain the same; a difference in letters and a change in meaning while the form remains the same; and a change in form while the meaning remains the same.