Unlike a levy, which involves intangible assets such as your bank account, a seizure is the taking of physical assets, such as your home or car. Seizures usually happen in aggravated cases when someone ignores many requests by the IRS over a long period of time to pay their outstanding taxes.
A seizure should not be taken lightly, as the IRS will ultimately pursue seizure of your physical assets. When the IRS seizes your assets, they want to quickly sell them at auction. They often get less than half the value of your asset, so they often seize everything you own, including your home, cars, boats, jewelry, motorcycles, insurance polices, and even your retirement funds.