Historically G4 and E4 suffixes meant “Green” or “Lead Free”. These standards have been phased into most products TI currently offers, meaning a part without a G4 suffix would still be Green and Lead Free, and is the same physical part as the G4 equivalent offering. As RoHS and Green offerings became standard in most parts, G4, or potentially E4 suffixes for a period of time were often still listed available for customers that needed a consistent orderable part number.
Texas Instruments G4 vs. no G4 suffix Currently there is no difference between a part numbers for example: SN74xxG4 and SN74xx
Due to this standardization, TI has recently been in the process of slowly phasing the environmental code suffix out of the manufacturer’s part number. Going forward G4 / E4 markings are still included on the physical part marking and on the manufacturer’s label to the left of the 2D bar code but will not be included at the end of the manufacturer’s part number on the label.
This is a summary of information TI has provided that can be found at the following FAQ: https://e2e.ti.com/support/logic/w/logicfaq/3545.07-part-numbers?tisearch=e2e-sitesearch&keymatch=g4
suffix For further information on what the G4/E4 suffixes mean can be found here: http://www.ti.com/lsds/ti/quality/environmental_info/lead-free/lead_free_conversion.page