This is more of an administrative change with regards to business focus of both companies as they are sister companies (or as MadBull say at their website, "Brother Companies). MadBull Airsoft officially takes over the licenced Daniel Defense line  that were under the SOCOM Gear Brand. Most likely that SOCOM Gear will focus more on the airsoft gas blowback line whilst MadBull will focus on the parts and licenced accessories.

All the Daniel Defense rails that are made under licence by MadBull are made in Taiwan using 6061-T6 aluminium, and hard anodized. These are fit for TM/Echo1/CA/JG and other TM-compatible AEGs (not the new gen TM AEGS). You won't be able to fit these rails on the real steel guns.

Check the website of MadBull Airsoft to learn more.