Not by a long shot. HIT has branched off so many times over the last decade that it's hard to nail down an exact definition. But for the most part, I'd say it means training low volume to failure (measure of intensity) with slower rep speeds.
HST is built around cycling rep ranges with intensity based off a % of max.
The differences will vary significantly though depending on which HIT program is being compared to HST.
The training programs themselves can look similar, especially if you're taking HIT from Arthur Jones and not Mentzer.
the rationale behind them is vastly different
This ties back into a discussion we had awhile ago about training theory vs training behavior. Good theories can produce bad behaviors; bad theories can produce good behavior. see majustu quote in my sig.