To me, the color means I am not sending/receiving images/video at full quality.
In my extended family, we even have both iMessage groups and WhatsApp groups, the iMessage ones specifically when we want to share original quality pics/videos of the kids and family for whoever wants to save them.
It's not an Apple thing, it's a carrier thing. MMS (green) data sizes are controlled by the carrier. WhatsApp doesn't use MMS and is a closed protocol.
iMessage (blue) sent messages are similarly a closed protocol and unencumbered by the carrier.
The destination carrier determines the maximum allowable size an MMS attachment can be:
Tier 1 Carriers -- Verizon, T-Mobile, AT&T -- all MMS content up to about 1 MB.
Tier 2 Carriers allow MMS content of 600 KB.
Tier 3 Carriers allow MMS content of 300 KB.
MMS (“green messages”) are mangled by most US carriers. The carrier will often recompress the media. And phones tend to send it at a lower quality to begin with.
I had never thought of doing that. I just tried, and clicking the + symbol in WhatsApp gives me option to send photos/video, documents, contact, and location.
If I choose documents, I do not see where I can go to select photos/videos in the iPhone camera roll. I presume it may not be accessible that way.
Also, I presume WhatsApp does not want to allow people to send photo/video at full size in their network to reduce bandwidth costs.
In my extended family, we even have both iMessage groups and WhatsApp groups, the iMessage ones specifically when we want to share original quality pics/videos of the kids and family for whoever wants to save them.