stock dividend就是从利润分配中挖一块给股本啊，stock split只不过是股票细分，股本总额不变。用会计语言描述，前者是借：利润分配，贷：股本，后者不做会计处理。

顶2楼。本人浅见：股票股利本质还是股利的一种，只是支付是通过给付一定数量的股票。不仅股票的数量而且整个的股本由于未分配利润转增资本而发生变化。与此相比，股票分拆时，股本和所有者权益都不发生变化，而由于分拆，股票数量增加，每股净资产和每股市价都会减少。股票分拆基本的考虑会是增加股票流动性，吸引投资者.

同意

Stock Splits

When a company declares a stock split, the price of the stock will decrease, but the number of shares will increase proportionately. For example, if you own 100 shares of a company that trades at $100 a share and it declares a two for one stock split, you will own a total of 200 shares at $50 a share after the split. A stock split has no effect on the value of what shareholders own. If the company pays a dividend, your dividends paid per share will also fall proportionately.

Companies often split their stock when they believe the price of their stock exceeds the amount smaller individual investors would be willing to pay for the stock. By reducing the price of the stock, companies try to make their stock more affordable to these investors.

Although many stock splits are two for one, companies can split their stock in any number of ways, including three for one, three for two, and so forth. A stock that has split in the last 52 weeks will be identified in newspaper stock columns with an "S" next to the company's name.

reference: http://www.sec.gov/answers/stocksplit.htm

stock dividend

Definition

A dividend paid as additional shares of stock rather than as cash. If dividends paid are in the form of cash, those dividends are taxable. When a company issues a stock dividend, rather than cash, there usually are not tax consequences until the shares are sold.

references: http://www.investorwords.com/4732/stock_dividend.html

stock dividend 是对于少量股票的分割，一般在5%-10%之间，stock split 是对于所有股票的分割，分割成2倍，3倍。

两种分割后，总股本等不变，根据CGA  FA3教材816-821页，他们的区别是：

The stock dividend chages both contributed capital and retained earning. The stock split , however, changes neither of those amounts.

contributed capital  是股票回购和库存股重新发行时价格与股票初始值之间的差额，它如果没有被冲销干净，这些差额计入retained earning。