Bhai Sahib Randhir Singh jee while explaining a Pankiti writes:
ਹਰਿ ਨਾਮ ਰਸਿਕ ਨਾਨਕ ਗੁਰ, ਰਾਜੁ ਜੋਗੁ ਤੈ ਮਾਣਿਓ॥6॥
(ਹੇ ਵਾਹਿਗੁਰੂ ਨਾਮ ਦੇ ਰਸੀਆਂ ਦੇ ਕਲਾ ਕੌਸ਼ਲੀ ਪਾਰਸ ਰਸਾਇਣੀ ਸੋਮੇ ਗੁਰ ਨਾਨਕ! ਰਾਜੁ ਤੇ ਜੋਗੁ ਕੇਵਲ ਤੈਂ ਹੀ ਮਾਣਿਆ ਹੈ। )
It seems like Raj and Jog are two different spiritual gifts that Siri Guru Nanak Dev jee Himself enjoyed and enabled his Gursikhs to enjoy as well. Raj represents that true spiritual kingdom and Jog represents it seems like represents the spiritual side. Siri Guru Sahibaan are the true Kings and everything occurs in this universe as per their Hukam and they are also the custodians of Gurmat Jog i.e. the way to meet Vaheguru.
When Guru Sahib does Kirpa, then His Gursikhs too do Raj Jog:
ਤੂੰ ਗੁਰ ਪ੍ਰਸਾਦਿ ਕਰਿ ਰਾਜ ਜੋਗੁ ॥1॥
(Do Raj Jog through Guru's grace.)
Gurmukhs who get accepted at the door of Guru Sahib do Raj Jog. They are Kings and Saints both at the same time.
Raj Jog also means that the way of Gurmat is not giving up the householder's life and becoming an ascetic. They do Raj (life householder's life) and also do Jog (Gurmat Bhagti).