The small Aleph of Vayikra versus the big Aleph of Adam:[1]
We find something very interesting in the beginning of the Parsha, that the word Vayikra is traditionally written with a small Aleph. This is in contrast to the book of Divrei Hayamim in which we find that the word Adam is written with a large Aleph.
Vayikra with small Alef: The reason that the Aleph of Vayikra is written small is because it represents a mere ray of a G-dly revelation that was given to Moshe in order so he could enter the tabernacle. In general, the letter Aleph comes from the word Pela and Alfecha Chochma which both represent a wondrous level that is above comprehension of which one exclaims amazement. The reason for this is because the letter Aleph is rooted in the Sefira of Keser which is above the level of wisdom. This level is so high that even Moshe cannot access it. It is for this purpose that the small Aleph was written, as it represents a mere ray of the attribute of Keser, which comes after many contractions of the original level. In order for Moshe to be able to enter the Ohel Moed, G-d draw down to him this ray of Keser.
Adam with big Alef: In contrast to this, the reason that by Adam the Aleph was written in large letters is because prior to the sin, Adam was on such a high level that he could receive from even a great revelation of G-dliness represented in the large Alef.
[1] Likkutei Torah p. 1a-2a
