Magento2 product_options field into the sales_order_itmes table

[gianluigi83f67]

Does anyone know why, sometimes, into the table sales_order_itmes, I see rows that has product_options fields like this:

{
    "info_buyRequest": {
        "uenc": "aHR0cHM6Ly9iZXRhLm5hdmlvbmljcy5jb20vaXRhL3BsYXRpbnVtLXBsdXMtbWVkaXRlcnJhbmVhbi1hbmQtYmxhY2stc2VhLTIuaHRtbA,,",
        "product": "16831",
        "selected_configurable_option": "",
        "related_product": "",
        "qty": "1",
        "super_attribute": {
            "140": "4"
        }
    }
}

and some other times I have this?

{
    "info_buyRequest": {
        "uenc": "aHR0cHM6Ly9iZXRhLm5hdmlvbmljcy5jb20vaXRhL2NoYXJ0cy9wcm9kdWN0L2luZGV4Lw,,",
        "product": "16132",
        "qty": 1
    }
}

Both are related to simple products (product_type column is 'simple')