Halliday & Matthiessen (1999: 122-3):
Texts and sequences are of the same order of abstraction; both are semantic phenomena. A text is a piece of language that is functional in context. It draws on the ideational meaning base but it involves the full metafunctional spectrum; i.e. there are interpersonal and textual contributions as well. Since text draws on the ideational meaning base, sequences are one principle for organising text. For example, the culinary procedure for making cauliflower surprise constitutes one text. Many text types are heavily influenced by patterns in the meaning base — they can be seen as 'macro-figures', i.e. as expansions of figures by means of logico-semantic relations. This is not to say that the relationship between organisation in the meaning base and discoursal organisation is always one-to-one even when a text is organised according to an ideational sequence. In particular, a text may leave to be inferred certain steps that would be specified in the sequence in the meaning base (e.g. to make explicit the inferential processes involved).