SN74LVC244ADBRE4 vs. SN74LVC244ADBRG4

I'll answer my own question:

The G4 suffix is the Pb-Free/Green designator. TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material).

The E4 suffix is the Pb-Free designator. During the initial conversion of Pb-free and green, the E4 and G4 suffixes were implemented to prevent customers from having to look at date codes to determine the lead free and green status of our devices. Once the standard part numbered devices are converted to the Pb-free and/or Green status, all devices; standard, lead free and/or green part numbers, are the same. The standard, G4 and E4 devices are all available, and none will be discontinued.