My friend works in China Merchants Bank.

His explanation is:

Fund account opening: an account used to purchase funds, but not for bank deposits.

And increase the fund trading account: it belongs to the bank account of fund transfer and can also be used to deposit funds.

Therefore, the nature of the two is different, the main difference is whether you can deposit funds. The fund account cannot deposit funds, but the fund trading account can.

I hope I can answer your question!