HOW TO DISTINGUISH Bl. yellow bird and Bl. memoria bernice foster
 

Anyone who have both the plants could help me as I am confused. I have searched internet both the plants have same type of flower. Now I am seeking help from the expert can anyone help me to identify which one is lb. Yellow bird and which one is memoria Bernice foster,

It will be impossible to tell them apart without a name tag. They share one parent. The flowers of the other two parents are quite similar.

Bl. Richard Mueller
= B. nodosa x C. (formerly Laelia) milleri

Bl. Bernice Foster
= Bl. Richard Mueller x B. subulifolia (synonym cordata)

Bl. Yellow Bird
= Bl. Richard Mueller x B. nodosa

B. nodosa and B. subulifolia have very similar flowers and foliage. They are different enough to be separated as species, but when used in hybrids, they are too similar to distinguish offspring. It would be like trying to distinguish the children of a bigamist man who married sisters.

If there any possibilities to identify by the flower size, or lip pattern or dot marks on the lip and after all by fragrance?

No

Individuals from crosses between such different parents exhibit a wide variation in all characteristics. There would be no way to tell them apart.

Almost all B. nodosa crosses have lip spotting, and it is highly variable between seedlings from a single pod. Same with flower size and lip pattern.

Most have no fragrance. Some have fragrance. It is unpredictable.