Similar Shabads? Why ?

Waheguru ji ka khalsa Waheguru Ji ki Fateh

There are many shabads which are repeated in Gurbani Eg:

"Pavan Guru Paani Pita" and ""Paun guru paani pita"" Ang 8 and Ang 146- Both means the same but why do they have different Words?

Like wise we have So dar keha So ghar keha in Japji Sahib and so dar tera keha so ghar Keha in Reharaas sahib

One reason could be that Guru Sahib wants us to be Suchet while reciting Gurbani so that we don't read Gurbani just for the sake of doing it.

It could be that just as Waheguru on one hand created many flowers, birds, shades of colours and so many other things which are very different from each other and on other there many which are very similar to each other, so He did in Gurbani. We can take these similar shabads to be like flowers of the similar kind.It could be there is no reason behind these similarities, its just Guru's Mauj.

Hanji Khalsaji.. This is Guru's Mauj No doubt but it should have something behind it like Siharis at the end of a shabad and aunknad has a meaning. Bhuk Chuk Maaf ji

Well veer jee with utmost respect...Guru baani/word/shabad/Guru baani ...message/// some times you never know when you will understand the deeper meaning...you will understand...once guru kirpa happens///pls don't worry about siharis//aunknad-leave you intellect aside/// the message will hit you like bolt of lightening, although the meaning may be very simple, it will touch your soul///all thing will fall in place...have faith///.............paapi....

There is some significance but there must be more to it than I understand.
One thing I am certain is that every single letter and associated grammatical presentation is there for some important reason which is sometime beyond our common intellect.

The 1st slok of pavan guru pani pita is by Guru Nanak ji mehla 1
the 2nd slok is by mehla 2.

There is also differences in the word ਦਿਨਸੁ(dinas) in the 2nd one compared to ਦਿਵਸੁ(divas) in the 1st one.
Also there is an additional of ''Hor'' ithe 2nd one with 'Nanak te mukh ujley HOR kethi chuti naal''

HOR= additional ...many more others.

Also, I undertstad PAVAN to mean the AIR as in the air of creation, the air in the atmosphere.. this is what was pit into the whole mass of maya creation FIRST. The Air..then water......
PAVAN is therefore the guru of maya to affect.

PAUN= is more than the air of atmosphere but it is implied for the specific air of breath. the LIFE FORCE...the one that sustains us...the sustaining energy that flows past our lungs.

I think that DIVAS is referring to the global phenomena of day and night on the planet whereas DINAS is referring to more about our own function with regards to Daily living and Night resting............However, someone more learned may correct me as punjabi is not my first language