Mr. Laser Beam wrote:
The difference is, the DTI does not actually travel in time. They only investigate incidents, they don't do any altering of their own. The Krenim do nothing BUT alter the timeline.
I think the OP is actually thinking of the Temporal Integrity Commission, the 29th century time cops from "Future's End" and "Relativity", rather than the 24th century DTI paper-pushers from "Trials and Tribble-ations"
As far as I know, only Annorax was altering the timeline with his massive ship and obsession with his wife. The advanced Krenim merely used their temporal torpedoes to slice through shields like they weren't there.