It really does not matter whether you say "Parvaan Karo" or "Bhog Lavo". If we get the great fortune of serving Sri Guru Ji in human form, it would not matter if we said, "Parshaada parvaan karo Sachay Paatshah" or "Bhog lavo Sache Paatshah". Either way the idea is for Guru Sahib to accept the sewa of Degh.
At the time when Guru Sahibaan were in human form, Degh was brought in their hazoori and they took degh before it was served in the sangat. Now that our Guru is Sri Guru Granth Sahib Ji, the degh is accepted by Guru Sahib through Kirpan Bhet.
As for the meaning of the word "bhog", it has many meanings in Sri Guru Granth Sahib Ji.
1) Completion of a task is said "Bhog pai giya" e.g. Sri Akhand Paath Sahib da bhog.
2) To enjoy the pleasures of the world is described as "bhog Bhogne" as is evident in the following pankiti:
ਮਿਰਤੁ ਨ ਆਵੀ ਚਿਤਿ ਤਿਸੁ ਅਹਿਨਿਸਿ ਭੋਗੈ ਭੋਗੁ ॥
(Death does not come in his mind; and night and day he revels in pleasures)
3) Every material requirement or substances we get from Waheguru are also called Bhog, as per the following pankiti:
ਦੇਦਾ ਰਹੈ ਨ ਚੂਕੈ ਭੋਗੁ ॥
(He continues to give, and His Provisions never run short.)
4) The act of Copulation is said to "Bhog karna" as in the following pankiti:
ਜੇ ਲਖ ਇਸਤਰੀਆ ਭੋਗ ਕਰਹਿ ਨਵ ਖੰਡ ਰਾਜੁ ਕਮਾਹਿ ॥
ਬਿਨੁ ਸਤਗੁਰ ਸੁਖੁ ਨ ਪਾਵਈ ਫਿਰਿ ਫਿਰਿ ਜੋਨੀ ਪਾਹਿ ॥੩॥
(Even if you do bhog with 100,000 women and become the kingdom of 9 continents, without the Satguru you will not get happiness and you will get into lifeforms again and again.)
ਕਾਇਆ ਕਾਮਣਿ ਜੇ ਕਰੀ ਭੋਗੇ ਭੋਗਣਹਾਰੁ ॥
(If I surrender my body like a bride, the Enjoyer will enjoy me.)
5) To eat too is referred to as "bhogna" as is the case in the following pankiti:
ਭੋਗਹੁ ਭੁੰਚਹੁ ਭਾਈਹੋ ਪਲੈ ਨਾਮੁ ਅਗਥਾ ॥
The pankiti quoted is as follows:
ਅਨਿਕ ਪ੍ਰਕਾਰ ਭੋਜਨ ਬਹੁ ਕੀਏ ਬਹੁ ਬਿੰਜਨ ਮਿਸਟਾਏ ॥
ਕਰੀ ਪਾਕਸਾਲ ਸੋਚ ਪਵਿਤ੍ਰਾ ਹੁਣਿ ਲਾਵਹੁ ਭੋਗੁ ਹਰਿ ਰਾਏ ॥੨॥
This is giving an example of a pativarta woman (a woman dedicated to her husband) who prepares many kinds of delicious foods after fully cleaning her kitchen and then in high anticipation requests her husband to accept the food she has prepared by eating it. Same way, the seeker of Waheguru does many acts of Gurmat including Naam Simran, Gurbani Paath, keeping rehit of Guru, sacrificing for Guru and Panth, giving up sensual pleasures of the world and then requests Waheguru to accept his sewa by giving darshan and accepting him.