Chomer is a quantitative concept, a physical mass. Tzurah is a more abstract, spiritual idea. The gemara [Moed Kotton 9a] talks about people who are אנשים של צורה - which Rashi explains this to mean "wise men". This is QUALITY and not quantity. Rov Moshe Feinstein was an אדם גדול even though he was barely 5 feet tall....:-). There was little chomer there but tremendous tzurah.
We spoke recently about how smell relates to tzurah. The gemara [Brachos 43] says that one's NESHAMA enjoys smell. That is because smell is tzurah-dik. This is unlike food and drink which is more coarse and physical - chomer. [There is a famous Bnei Yisaschar Torah that the only one of the five senses that Adam Harishon didn't sin with was his sense of smell. Smell remains holy...]
There are many arguments in the gemara that revolve around the question of whether reality is primarily defined as chomer or tzurah. How does the Torah perceive reality - Through the physical, quantitative aspect or the spiritual, qualitative aspect?
If someone gives a get and writes in the get that you are divorced from me but still forbidden to all other men - the get is not valid. When one divorces a women she must be permitted to everybody else. However, rabbinically the get is valid [according to the Rambam Geirsuhin 10/1] and she may no longer marry a kohen as a divorcee [but see Tosfos gittin 82a that min hatorah she may no longer marry a kohen]. This is called ..... ריח הגט. It smells of a get.
How does a get smell??????
Here Chazal are telling us that this is not a concrete, hard core, "the real McCoy" type get. It is [Rogochover-ly] צורת גירושין. A more subtle, abstract type of get. A real get allows her to marry anyone she chooses while this get just makes her considered a divorcee insofar as that she may no longer marry a kohen.
Beis Shammai, as we aleady discussed, assigned more value to tzurah than Beis Hillel. A few examples:
1] If a person writes a get for his wife and then changes his mind and decides not to divorce her, Beis Shammai says that she may no longer marry a kohen because this get has ריח הגט. [Gittin 81a]
2] Beis Shammai says that if someone writes one letter of Hashem's name it is considered holy [Yerushalmi Sotah 2/4]. [Beis Hillel says that you need two letters.] Just the thought that this will be part of Hashem's name is enough to make it holy.
3] If a custodian intends [see Rashi] to misappropriate a deposit, Beis Shammai says that he is liable for any mishap that might befall the deposit. Beis Hillel says that he doesn't assume liability until he actually misappropriates it [Bava Metzia 43b]. In other words - Beis Shammai follows the tzurah, the machshava, the intent. He holds that one can perform משיכה on the object without actually touching it. This is called משיכה צורנית. Beis Hillel says that tzurah is not enough. He needs to actually use the object for his own needs in order to be liable - חומר.
לזכות טובה בת תילה לזרעא של קיימא די לא יפסוק ודי לא יבטול מפתגמי אורייתא