LLC members are taxed on their personal tax returns. The LLC itself is not taxed. S-Corp shareholders are taxed on their personal tax returns. The company itself is not taxed. C-Corps are taxed both at the corporate level and again on shareholders' individual returns. Non-Profits are taxed on a corporate level but may also enjoy a host of tax-exempt benefits. Sole Proprietorships are taxed only on their owner's tax return.
LP, Limited partnership: a partnership where at least one partner (the general partner, which may itself be an entity or an individual) has unlimited liability for the LP's debts and one or more partners (the limited partners) have limited liability (which means that they are not responsible for the LP's debts beyond the amount they agreed to invest). Limited partners generally do not participate in the management of the entity or its business.