Namely, you need to have been continuously and ordinarily resident in the HKSAR for at least 7 years in or to qualify for either of these immigration consents.
But, whilst the right of abode is the Rolls Royce immigration status representing defacto Hong Kong citizenship (albeit without a passport if you’re not a Chinese national), unconditional stay is merely an administrative convenience afforded to you by the Director of Immigration.
If you have the right of abode in Hong Kong you get:
• to land
• to be free from any condition of stay (including a limit of stay)
• not to be deported; and
• not to be removed.
Moreover, so long as you make one entry into Hong Kong in any 3 year given period, you will not lose your right of abode. If you fail to meet this condition, however, you are simply downgraded to the right to land.
If you only go for unconditional stay, though, you are allowed to remain here unconditionally, meaning no sponsor or further permission of the Immigration Department are needed to live out your time in the HKSAR, but you will lose this status if you are absent from Hong Kong for more than 365 continuous days in a row.
So, most people who qualify for upgraded immigration status after living continuously in Hong Kong for 7 years go on to secure the right of abode bypassing unconditional stay completely.
However, for those long stay residents who have not taken Hong Kong as their only place of permanent residence or for Capital Investment Entrant Scheme visa holders who have not lived full time in Hong Kong during the 7 years of holding that status, Unconditional Stay is an obvious choice to go for.