These are American titles.
In the definitions section of types of analysis prepared for the Virginia Department of Transport:
Modification Impact Analysis (U.S. Army Corps of Engineers) – a contemporaneous
schedule impact analysis technique in which at the time of modification, the
actual status of the job is determined, the schedule is updated, and the delay is
inserted to quantify singular impact
Time Impact Analysis – similar to the Modification Impact Analysis, a schedule impact
analysis technique that recreates the actual status of the job at the time of
modification, updates the schedule, inserts delays, and quantifies singular impact;
although retrospective in that it is done after the fact, it has a contemporaneous
orientation, not a hindsight perspective
Schedule Impact – the potential effect of a delay or change on a project schedule; may
be in the form of delay or change in project completion date, delay or change in
project sequence, or consumption of float
Schedule Impact Analysis (SIA) – the process of quantifying and apportioning the
effect of delay or change on the project schedule.
Which appears to mean that TIA is used for work in progress and SIA is forensic (or maybe not).