Are there any major differences between the GRCh38 (NCBI) and hg38(UCSC) databases, aside from the fact that GRCh38 uses a 1-based coordinate system, while UCSC uses a 0-based coordinate system? Are there any pros/cons in using one vs the other? And, I am guessing that any identifier conversion software (e.g, BioMart) should choose one database over the other? Also, where does Ensembl come into play? Is the Ensembl database just a subset of the GRCh38 (NCBI) database? Any clarification would be greatly appreciated.