Halliday & Matthiessen (1999: 132):
Doing involves a change over time of occurrence (including maintaining a state in spite of force for change). The change may take place along any one of a number of dimensions:
(a) circumstantial: spatial (motion or disposition, concrete or abstract);
(b) intensive: qualitative (colour, size, shape, solidity, etc.), quantitative (increase, decrease);
(c) possessive (transfer of ownership, loss or accretion of parts);(d) existential (creation or destruction).
In contrast, being does not depend on any change over time. As a figure of being unfolds over time, the only change is that embodied in the temporal unfolding of the process itself. The nature of the actualisation will be the same at any point in time.