The kind of restriction depends on the listener's prior supposition. Qaṣr al-qalb reverses an incorrect attribution to another agent. Qaṣr al-ifrād denies the presumed participation of several agents and isolates the intended one.
Hearer's suppositionSpeaker's correction
ʿAmr acted, not IReversal: I am the real agent
ʿAmr and I both actedExclusion: the other participant is denied
A single surface form may therefore express different rhetorical kinds of restriction depending on the misconception being corrected.