Martin (1992: 182):
The centrality of the internal/external distinction to an adequate account of the discourse semantics of logical relations is the main factor distinguishing Halliday's (1985) classification of expansion from that being developed here. The internal/external opposition does not play a part in Halliday's (1985) discussion because his focus is on the clause complex in relation to the rest of the grammar, rather than in relation to cohesion and text structure. In particular, a good deal of his elaboration category is reinterpreted here as simply the internal face of comparative similarity rather than as a major logico-semantic category in its own right.
 The main factor distinguishing Halliday's (1985) model and Martin's (1992), apart from the fact that Halliday's model is original and Martin's model is a reworking of Halliday's, is that Martin's model ignores the metafunctional distinction between logico-semantic relations between clauses (logical) and conjunctive cohesion (textual). Halliday & Matthiessen (2004: 538-9):
… logico-semantic relations are confined to the internal organisation of each clause complex: the clause complex is the most extensive domain of relational organisation. The cohesive system of conjunction has evolved as a complementary resource for creating and interpreting text. It provides the resources for marking logico-semantic relationships that obtain between text spans of varying extent, ranging from clauses within clause complexes to long spans of a paragraph or more.
 In SFL theory, internal relations may obtain in logical relations between clauses in complexes, and in conjunctive cohesion, the non-structural resource of the textual metafunction for marking textual transitions. On internal logical relations between clauses, Halliday & Matthiessen (2004: 419) write:
… the enhancing relation may be internal rather than external; that is, the beta-clause may relate to the enactment of the proposition or proposal realised by the alpha-clause rather than to the figure that it represents. For example, if it is not too personal an inquiry, what limits do you set… means ‘if it is not…, I ask you…’; that is, the condition is on the act of questioning, not on the content of the question.On internal relations in conjunctive cohesion, Halliday & Matthiessen (2004: 545) write:
Many temporal conjunctives have an ‘internal’ as well as an ‘external’ interpretation; that is, the time they refer to is the temporal unfolding of the discourse itself, not the temporal sequence of the processes referred to. In terms of the functional components of semantics, it is interpersonal not experiential time.
 This is a serious category error — enhancement and elaboration are distinct logico-semantic types. As a transphenomenal fractal type manifest at different scales across various domains, comparison is a subtype of the enhancement category manner.
 As a transphenomenal fractal type manifest at different scales across various domains, elaboration is a major logico-semantic category, contrasting with extension and enhancement within expansion. For example, the distinction between 'intensive', 'possessive' and 'circumstantial' relational processes, identifying and attributive, is the distinction between elaboration, extension and enhancement, respectively.