Motifs vs. snippets: While motifs reward fidelity of conservation, snippets also rewards coverage.
Informally, coverage is some measure of how much of the data is explained or represented by
a given snippet.
Shapelets vs. snippets: shapelets are defined as subsequences that are maximally representative
of a class. Shapelets are supervised, snippets are unsupervised. Shapelets are generally biased
to be as short as possible. In contrast, we want snippets to be longer, to intuitively capture
the "flavor" of the time series.