When assets are frozen as part of a criminal case, they can't be moved or released at all by the institute holding them. At the conclusion of the criminal case, if the defendant is not guilty or the case is dropped, then they're simply unfrozen. If the defendant is found guilty, then any fines and fees will be seized from them and the remaining amount unfrozen. At all times, those assets have not moved at all. Additionally, frozen assets can be authorized to be released to pay for a defense or living expenses by the court during the case and appeals.
When assets are forfeited, they're seized by the government and just tossed somewhere likely to get lost (tons of things get lost, damaged, and stolen when seized). If you even have the money left to hire a lawyer, you might be able to contest the forfeiture. But because the assets and not you are being charged, well they don't have to try very hard to let you know of the case. In almost all cases, the assets are forfeited summarily because people can't afford to get them back or they're notified too late to find an attorney and start the process of contesting the forfeiture. This process is colloquially known as theft.
When assets are forfeited, they're seized by the government and just tossed somewhere likely to get lost (tons of things get lost, damaged, and stolen when seized). If you even have the money left to hire a lawyer, you might be able to contest the forfeiture. But because the assets and not you are being charged, well they don't have to try very hard to let you know of the case. In almost all cases, the assets are forfeited summarily because people can't afford to get them back or they're notified too late to find an attorney and start the process of contesting the forfeiture. This process is colloquially known as theft.