Enya International Musical Instruments Co. Ltd. (Group Headquarters), is responsible for all the group arrangements, company's operations and development plans, including OEM deals. It is also responsible for the Enya and Kaka, (often with a big K or Ka on the headstock), brand products global promotion and sale. 

Huizhou Jiyi Musical Instruments Co. Ltd. is responsible for all factory production management, quality control, shipping systems and logistics business. This is the makeup and division of work in the business according to one source of information and it sounds reasonable to me?. The reason I am not more certain is there are a number of places on the web talking about the firm and not all of the information they give is consistent. For example they say they were founded in 2009 and 2011, (on one site it says this in the same section!) by a man called Haiming Hu. This is possible if the two firms started at different times; but nowhere have I seen this suggested. I am sure Jiyi is based in Huiyang, Huizhou, Guangdong, (Enya just Huizhou), and they claim to have a factory that employs over 100 people, (Enya 300), making high end Guitars. Some of the sources are a little dated now so some of this may have been true once but things have moved on? So 5 years ago they may have had an office in California but now the US office is definitely in Houston, Texas. 

Kaka is usually the more budget of the two brands and I have seen Mini to Tenor scales but no extra string options. Enya can still be fairly budget but they do go up to some very high end models and claim to make a fully Carbon Fibre models, (I have one and it doesn't feel like Carbon Fibre to me?) Enya also make Guitars.

Some other brands they do own and distribute include Century and O.M.S. There may be more I haven't come across? (There is also a Guitar brand called Amari but I've not seen this on a Ukulele). They are also the company that have the official licence for and make Minions Ukuleles. 

They claim to be the OEM for Peavey, Lag and Lanikai? but I'm suspicious of this, I do believe they were the Chinese supplier for ÖzÜn though and if they don't own the Irin brand name they are certainly a major OEM for them.

There is a fair amount of crossover between the brands for example I have seen the Kaka pony on Enya Kalimba and I have seen tenors with the Kaka K on the headstock and Enya inlaid as 12th fret marker 

On some old sites they say they own the brand name Tom but I don't think they do, (they may have made or distributed some in the past but apart from the one statement on the website there is no further links and on the Tom website it lists a different parent company (Also I own a Tom Mini and a Kaka Mini; and they are obviously made by different factories).