A stock dividend isn't exactly a split.
Example:
You have 100 shares of stock worth $5 a share (total value $500). The company wants to distribute a dividend worth 1%. You could expect a check for $5. But If they wanted to do a stock dividend they could send you 0.01 shares for every share you own, in your case you will be given a single share worth $5. Now you own 101 shares.
Why a share dividend? It doesn't take cash to give the dividend. It keeps the money invested in the company. Some investors re-invest a cash dividend, some don't. A cash dividend is generally taxable income for the investor; a stock dividend isn't. Some investors prefer one over the other, but it depends on their specific financial picture.
Neither a stock dividend, a cash dividend or split changes anything. The split changes the price to meet a goal. The cash dividend lowers the price by sending excess cash to the investors. The stock dividend lowers the price by creating new shares and retaining cash.
It company picks the message and the method. depending on their goals and situation. Remember that a company may want to give a dividend because they have a history of doing so, but not have the cash to do so.
It is like a split because the number of shares you own will go up, and the price per share will go down. But a split is generally done to bring the price of a share to within a specific range. The company sees a benefit to having a stock mid priced, instead of very high or very low.