Both the MACCS FP and random walk feature vector characterize a molecular graph by looking for a list of "patterns" in it-subgraph patterns for the MACCS FP and label sequences along walks for the random walk feature vector. Distinctions are: (1) the MACCS FP looks for variable-size subgraphs, whereas the random walk feature vector looks at fixed-size (length) label sequences along walks; (2) the random walk feature vector counts patterns, whereas the MACCS FP only indicates the presence of patterns; (3) the random walk feature vector exhaustively counts all possible walk patterns, while the MACCS FP non-exhaustively looks for a pre-defined, curated subset of the possible subgraph patterns; (4) owing to the variably-sized list of subgraph patterns including wildcard atoms/bonds, in the MACCS FP, multiple subgraphs can activate the same bit, and a single subgraph can activate multiple bits; (5) the MACCS FPs φ MACCS (G) ∈ R 166 are feasible to explicitly construct and store in memory, while the fixed-length random walk feature vectors φ (L) (G) ∈ R S L are not for large L, owing to the large number of possible label sequences S L present in length-L walks on molecular graphs .