A few technical points on tax (of course, check with your professional advisor for any real-world case):
1. IRC 83(a) sets the baseline: you are taxed on the value of property (stock) received in exchange for services as ordinary income. IRC 83(b) says that you do not receive such property immediately if it is subject to a "substantial risk of forfeiture" and that you will be taxed on it only when the forfeiture risk lapses and you truly own it. Thus, with restricted stock, you are subject to tax at ordinary income rates on the difference between what you paid for it and what its value is at each vesting point. If your 1M shares vest at 1/48th per month over 4 years, and you paid $.001/sh, you would have to pay tax on the "spread' at each vesting point as long as the price exceeded $.001/sh at that point. This theoretically could mean that you have as many as 48 taxable events during the 4-year period of vesting. All of this, of course, is done away with if you file a timely 83(b) election. In that case, you normally pay no tax up front and you pay only capital-gains tax on the stock as you later sell it. This is the optimum tax treatment for most startups but is normally made available only to founders.
2. Now what about options. The default rule here concerns so-called "non-qualified" options (NQOs, sometimes called NSOs as well, for "non-statutory options"). The substantive law rules relating to such options are the same as any other options and they are "non-qualified" only in the sense that they don't qualify for the special tax advantage of "incentive stock options" or ISOs, which are special types of options that get special tax advantages. To understand ISOs, you need to understand how all options are taxed apart from any special tax-advantaged rules.
3. With NQOs, you get a right to buy company stock at a fixed strike price exercisable as your options vest over a prescribed period. If your strike price is $.001/sh, and you exercise 1M options, you pay $1,000 to get 1M shares of stock. If the fair market value of that stock is $.001/sh at the time you exercise, you pay $1,000 for stock worth $1,000 and you realize no taxable income. If, however, the fair value of the stock is worth more (let us say, $.20/sh) and you exercise your first increment of (say) 250K shares at year one of vesting on a 4-year plan, then you realize $49,750 worth of taxable income upon your exercise. This is taxed at ordinary income tax rates and the amount is factored into your employment income so that you effectively pay all normal employment taxes on it as well (social security, etc.). Hence, with NQOs, you pay tax on the "spread" at ordinary income tax rates upon each exercise. When the transaction is done, you very likely will hold illiquid stock, you will have no cash from the transaction with which to pay the tax, and you are generally in a highly disadvantageous tax position. Once you make the exercise, any later appreciation on it is not taxed until you sell it and, at that time, you will be taxed on that subsequent appreciation at capital gains rates.
4. With ISOs, when you exercise your options, you are not subject to an immediate tax based on ordinary income tax rates and this is the special tax advantage that ISOs have. The idea is that, with these tax-advantaged options, employees should feel free to buy their shares by exercising their options whenever they like (once they have vested) and will only be subject to tax at the time they ultimately sell the shares. Having exercised and bought the shares, your holding period begins to run and, if you hold them for the prescribed period (which, in the case of ISOs, is 2 years), you pay LTCG rates - all in all, a huge advantage over the NQO tax treatment. But there is a clinker with ISOs and this is the AMT, or alternative minimum tax. With an ISO exercise, the spread amount is includable in your income for purposes of calculating your AMT and, therefore, even though you may not have to pay tax at ordinary income tax rates on the value of the spread, you may wind up paying a substantial tax under the alternative measure applied by U.S. tax laws. This means that, in a high-value company, you definitely need to check with your tax advisor to determine your tax hit prior to doing such an exercise.
5. ISOs granted with an early-exercise privilege (as noted in this piece) are taxed substantially the same as restricted stock and this is a huge advantage. However, startups do not normally offer this privilege for various reasons (mainly because it is a mistake to make large numbers of employees instant shareholders) and so it is not really a practical answer to most such situations.
6. Thus, restricted stock is near-ideal from a tax standpoint, avoiding most tax risks and positioning your holdings for LTCG treatment, but is normally granted only to a very few people (mostly founders). ISOs avoid ordinary income but may subject you to an AMT tax hit - in addition, they can be used only with employees. NQOs are least favorable, subjecting you to an ordinary income tax hit on any spread as of the date of exercise, but these are valuable for their flexibility (they can be used for contractors, directors, and others besides employees).