The distinctions between the individual components of an Equity section (e.g., Common Stock, Add'l Paid-in Cap, and so on) are largely a traditional carryover of the need for corporations to separately track things like the par value of issued shares, vs. amounts paid by investors
over the stated par value, etc.
A lot of smaller, closely-held companies like to distinguish between the capital the founders initially put into the company at start-up, versus any subsequent capital infusions they make down the road to "feed the kitty" when corporate cash gets low. These companies will frequently use two separate Equity accounts to keep track of the two, and a lot of times they'll use the title "
Additional Paid in Capital" for the account into which the subsequent capital investments are credited.
They could just as well call these two Equity accounts "
Start Up Investment" and "
Later Investments", but "
Capital Stock" and "
APIC" sound cooler, and besides, it's what the big corporations all have on
their balance sheets
Set up your Equity section in whatever manner is most useful and meaningful to the owners of your company. For example, I recently worked with a client that had 3 different types of
Owners' Draws accounts and several different kinds of
Owners' Investments accounts in the Equity section of the Bal Sheet. Why? Because they were fanatical about keeping track of every different type of Draw and Investment. I explained to them that they could just as easily keep track of all these differences on a spreadsheet, and thereby streamline their balance sheet down to just two or three Equity accounts. But they were adament about seeing all those different accounts right there on the face of the Bal Sheet.
Point is, use whatever arrangement (including account names) that gives the owners the info they want. One caveat: If you also furnish financials to outside parties (investors, lenders, banks) check the contracts and the loan agreements to see what kind of financial statement presentation they require---it may be different than the internal financials you give to the owners.
Cheers!