Steady application of microevolution results in, on the higher scale, the potential for spurts and stops in macroevolution. They might be useful concepts to discern between, might not. But they’re both the same mechanism – evolution. Just acting on different scales. Growth vs pubescent growth, you could tell apart by hormonal changes, whereas you wouldn’t be able to examine a species and say whether they’re busily macroevolving or microevolving; just that they’re evolving (and they will be, all the time, so long as they’re reproducing, have some variation and there are selective pressures present).

Mutation occurs at a more or less constant rate, but most of them will occur in non-coding DNA (some of which will have regulatory functions or uses we don’t know about, but much of which is truly junk) Within coding DNA many mutations will be masked by the redundancy of the codon to amino acid translation. Amino acid changes may not affect the structure of the protein protein. A protein can change without affecting its function, and a functional protein can sometimes be changed without adaptive consequences.

So that’s a lot of neutral mutations that won’t do a lot except generate a little bit of diversity in the genome. Then we get the ones that do something; some are deleterious and lost, some are advantageous in some way. Each within that advantageous set will have differing degrees of actual effect on the organism and hence different degrees of ‘novelty’ and adaptive value. Then there’s environmental factors – the degree of pressure on an organism won’t affect how often beneficial mutations occur but it’ll affect how quickly they spread.

So a constant tick rate of mutations will give you a relatively steady stream of minor changes, which might over long enough time frames effect substantial change in a species or cause speciation. Then every so not so often you get a mutation that’s something we later see to be big and noticeable and important, that offers sufficient benefit to sweep through a population and be the next “step forward”.

Steady microevolution, bursty macroevolution. Constant rate of mutation.