It makes no difference. If you have to be careful, I personally understand that "subscription" is a transaction that describes the primary market, and "purchase" refers to a transaction that describes the secondary market.

"Fund share subscription" means that you buy the fund of the fund company (that is, ordinary open-end fund) on and off the market. "Fund share purchase" means that you bid for funds (such as closed-end funds and LOF market share) in the market.