pre_text: Restricted Stock Unit Award Plans We have two Restricted Stock Unit Award Plans for our employees and non-employee directors, a 2017 Restricted Stock Unit Award Plan (the “2017 RSU Plan”) and a 2014 Restricted Stock Unit Award Plan (the “2014 RSU Plan”). Vesting of an RSU entitles the holder to receive a share of our common stock on a distribution date. Our non-employee director awards allow for non-employee directors to receive payment in cash, instead of stock, for up to 40% of each RSU award. The portion of the RSU awards subject to cash settlement are recorded as a liability in the Company’s consolidated balance sheet as they vest and being marked-to-market each reporting period until they are distributed. The liability was $29 thousand and $11 thousand at December 31, 2019 and 2018, respectively. The compensation cost to be incurred on a granted RSU without a cash settlement option is the RSU’s fair value, which is the market price of our common stock on the date of grant, less its exercise cost. The compensation cost is amortized to expense and recorded to additional paid-in capital over the vesting period of the RSU award. A summary of the grants under the RSU Plans as of December 31, 2019 and 2018, and for the year then ended consisted of the following (in thousands):
table: Year Ended December 31,
table: 2019 2018
table: Number of Number of Number of Number of
table: RSUs Vested RSUs RSUs Vested RSUs
table: Outstanding, Jan. 1 951 459 462 262
table: Granted 333 - 759 -
table: Distributed (267) (267) (262) (262)
table: Vested - 825 - 459
table: Forfeited - - (8) -
table: Outstanding, Dec. 31 1,017 1,017 951 459
question: Analyse this data from a financial earnings document. What is the difference between ending outstanding balance of RSUs and Vested RSUs in 2018?