Some Matzah bakeries offer two different types of Matzah; one called Rasham and the second called Rashi. The Rashi Matzas are traditionally more expensive. To the unaware, this may seem like Matzas which follow two different opinions of Rishonim, however, in truth it does not refer to any person or opinion but rather to the form of grinding. Rashi means “Reichaim Shel Yad” or hand ground Matzah. Some opinions require that the grains be made into flour by a Jew. Rasham means “Reichaim Shel Mechona”, or machine ground flour. Admur rules that there is no need for a Jew to grind the Matzas, as stated above, and hence, in his opinion, there is no need to purchase the more expensive Matzah called Rashi. Other Poskim concord with this view and negate the stringency of Rashi Matzos.
Matzah’s Mitzvah-Guarding the grains for the sake of Pesach:
On the first night of Pesach, one only fulfills the Mitzvah of eating Matzah, with Matzah that had its grains supervised from becoming Chametz for the sake of Pesach, for the sake of Matza’s Mitzvah [i.e. Lishma]. [Meaning, that in addition to the fact that all Matzos eaten over Pesach must be guarded from Chametz, the Matzos eaten on the night of the 15th/16th must also be guarded Lishma, for the sake of the Mitzvah.] Some Poskim rule it must be guarded for the sake of the Mitzvah to eat Matzah on the night of the 15th of Pesach. However, other Poskim rule that it suffices to guard it for the sake of the Mitzvah of eating Matzah throughout the seven days of Pesach. Practically, the main opinion follows this latter approach. Any Matzah which was not made Lisheim Matzas Mitzvah may not be used on the first night of Pesach for the sake of the Mitzvah, even if it was guarded from the time of harvest from becoming Chametz.
Must a Jew grind the kernels? The grinding of the kernels for Matzas Mitzvah may be done by a gentile, as long as there is a Jew who is supervising him, and thus guarding the grains from becoming Chametz.
The kneading: The kneading, rolling and baking of the Matzah’s Mitzvah eaten on the first night of Pesach, is disputed amongst the Poskim if it must be performed by an adult Jew for it to carry the status of Lishma, and practically we are initially stringent. The person doing the kneading recites Lesheim Matzas Mitzva when place the flour into the bowl and when he places the water into the flour.
Should one eat Shmura Matzah on all days of Pesach? The Jewish people are holy and are accustomed to eat Shmura Matzah all the days of Pesach, and not just for Matzas Mitzvah of the first night.
 Bach 453; P”M 460; Biur Halacha 460 “Ein Lashin”; See Piskeiy Teshuvos 450:6; Regarding the custom of the Chabad Rabbeim, and the original custom in Libavitch-see Otzer Minhagei Chabad 11 that a hand mill was used.
 Admur 453:16; Taz 460:1; Chok Yaakov; Chasam Sofer 128; Shaareiy Teshuvah 453:8
 Beir Moshe 7 Kuntrus Elektri 49; Az Nidbaru 5:34
 Admur 453:14
 The source: This is learned from the verse “Ushmartam Es Hamatzos”, which means that the Matzos are to be guarded for the sake of the Mitzvah of Matzah. [Admur ibid]
 M”B 453:21
 See Admur 477:10
 Admur 453:16; Taz 460:1; Chok Yaakov; Chasam Sofer 128; Shaareiy Teshuvah 453:8; The grinding, unlike the kneading, may be done by a gentile, as long as there is a sane Jew who is supervising him, and thus guarding the grains from becoming chameitz.
Other opinions: The Bach rules that this is dependent on the dispute in 460 regarding kneading. Practically, the P”M 460 and Biur Halacha 460 rule that due to this, if possible it is proper to get Matzos that were ground by hand and not machine. However, clearly according to Admur there is no need for this stringency. These two forms of grinding have found their difference in the names Rasham and Rashi, which mean Reichaim Shel Yad Or Mechona [hand ground or machine ground].
 Admur 460:1