Mubarak225:
Asalam alaykum dear brother and sister in islam on this forum.
My question is: can someone help me to diffeciate between sujud badh and sujud qadr.

Hi Mubarak,

I suppose you meant to enquire of the two sujuudu saah'wi(s) i.e qabl and baa'di.

So, when praying and mistake(s) arise(s),those are the two categories of sujuuds we can use to correct them.

Qabl

This is the type of sujuud done to rectify salah when we make an ommission. it is done before the tesleem.

- If the Omission is a sunnah e.g forgetting to say "Ameen" after Fatiha, when you remember this, it's not compulsory to do saah'w (but there's a caveat on this). In summary, when the ommission is a Sunnah on Salat, then saah'w is not compulsory.

- If the omission is a waajib, then saah'w is required to rectify the omission. for instance, forgetting to sit for the first tashaahuud and remembering when one has fully rose to the third rak'ah. If one has stood completely to the third raka'h, then there is no need to go back to do tashaahud. but saah'w is required.


Baa'di

This is the type of sujuud done to rectify an addition. it is done after the tasleem.

All the ifs apply to Baa'di as well,with respect to whether the addition is a sunnah or a waajib or a ruknu.

ruuknu are those aspect of sallah without which the sallah is utterly invalidated.

for example reading Faatihah, doing taakbiraatul ihram while standing upright, rukuuh, sujud.

When there is an addition of a ruknu and we realize after the addition is made, then only baa'di is required.

But when a ruknu is omitted, then we need to bring that rakaa'h where the omission was perpetrated again. for instance, you did just one sujuud in the second rakaah. but then you only realized this when you were on the 3rd rakaah, then you need to take the 3rd rakaah as the second (as the former second rakaah is invalid now). then a Baa'di will be required in this regard on the 5th [now the 4th] rakaah.

the case is different when we are in doubt about the mistake. but I'll rest here and let the sheikhs have the floor.