What is the difference between ’Nichsei Melog’ and ’Nichsei Tzon Barzel'?

The estate the wife brings into the partnership are divided into two categories "Nichsei Melog" and "Nichsei Tzon Barzel" Melog – Estates the wife brings into the partnership which is not listed in the Ketubah, or estates she brings in after the marriage takes place. These are her estates and the husband only gets to use them for their produce (i.e. fruit of the a field, rent of a house) In the case of a divorce or husbands death, she gets the estate back as it is regardless of its initial value. Tzon Barzel - These estates were brought into the partnership by the wife and listed in the Ketubah (Nedunyah – Dowry). The husband can use them as he wants and he gets to keep the profit of the increased value of the asset. In case of divorce or husbands death, she gets the value of the original asset regardless of its current value.