A method, implemented at a computer system that includes at least one processor, for diffing a subject replayable execution trace against a comparison replayable execution trace, the method comprising: accessing a first subject replayable execution trace (300, 401a, 402a, 403a) which represents a first sequence of executable instructions that executed as part of a first executing entity, and accessing a second comparison replayable execution trace (300, 401b, 402b, 403b) which represents a second sequence of executable instructions that executed as part of a second executing entity; identifying a first plurality of functions within the first sequence of executable instructions, and identifying a second plurality of functions within the second sequence of executable instructions, each function corresponding to a sequence of one or more executable instructions that executed as part of the function; identifying a first plurality of groups of the first plurality of functions, and identifying a second plurality of groups of the second plurality of functions, each group comprising a sequence of one or more related functions; comparing the first plurality of groups and the second plurality of groups, including determining, based on an identity of each group and on one or more functions corresponding to the group, if each first group in the first plurality of groups is at least one of: equal to a second group in the second plurality of groups; a replacement of a second group in the second plurality of groups; deleted from the second plurality of groups; or inserted into the second plurality of groups, wherein the comparison is performed by measuring a minimum cost of one or more single-item edits required to transform one sequence into another sequence, a single-item edit being one of an insertion, a deletion or a replacement; and providing one or more indicia of a result of the comparing to a software component at the computer system, or to another computer system, the one or more indicia indicating whether each first group is at least one of equal to a second group in the second plurality of groups, a replacement of a second group in the second plurality of groups, deleted from the second plurality of groups, or inserted into the second plurality of groups. accessing a first subject replayable execution trace (300, 401a, 402a, 403a) which represents a first sequence of executable instructions that executed as part of a first executing entity, and accessing a second comparison replayable execution trace (300, 401b, 402b, 403b) which represents a second sequence of executable instructions that executed as part of a second executing entity; identifying a first plurality of functions within the first sequence of executable instructions, and identifying a second plurality of functions within the second sequence of executable instructions, each function corresponding to a sequence of one or more executable instructions that executed as part of the function; identifying a first plurality of groups of the first plurality of functions, and identifying a second plurality of groups of the second plurality of functions, each group comprising a sequence of one or more related functions; comparing the first plurality of groups and the second plurality of groups, including determining, based on an identity of each group and on one or more functions corresponding to the group, if each first group in the first plurality of groups is at least one of: equal to a second group in the second plurality of groups; a replacement of a second group in the second plurality of groups; deleted from the second plurality of groups; or inserted into the second plurality of groups, equal to a second group in the second plurality of groups; a replacement of a second group in the second plurality of groups; deleted from the second plurality of groups; or inserted into the second plurality of groups, wherein the comparison is performed by measuring a minimum cost of one or more single-item edits required to transform one sequence into another sequence, a single-item edit being one of an insertion, a deletion or a replacement; and providing one or more indicia of a result of the comparing to a software component at the computer system, or to another computer system, the one or more indicia indicating whether each first group is at least one of equal to a second group in the second plurality of groups, a replacement of a second group in the second plurality of groups, deleted from the second plurality of groups, or inserted into the second plurality of groups.