When someone wants to gift a piece of property in the U.S., there is a need to pay a gift tax. If the gift happens to be stocks, cash, or even intangible property, the tax is typically paid by the person who gives the gift – unless they retain an interest in the gift that ends up delaying act of giving the gift.
A gift is just a gift when it changes hands without anything of value being exchanged. A gift is partially just a gift if the person giving the gift gets something in return for it, but the property received is a great deal less than the value of the property given. The amount of the gift in situations like that is the difference between that given to the recipient and what the recipient gives in return.
In general, if interest in property is transferred while the giver is alive, it would not be subject to estate tax. Congress blended the estate and gift taxes in 1976, which restricted the giver’s ability to get around estate tax by giving the property when they were alive. Despite that, there are differences between gift and estate taxes. E.g. the effective tax rate. Other differences are best explained by an attorney.