7. The styles of blessings:[1]

Bracha Ketzara or Matbeia Ketzara: A Bracha Ketzara or Matbeia Ketzara refers to a one sentence blessing, such as a typical blessing which is recited prior to eating food or prior to performing a Mitzvah.

Bracha Arucha or Matbeia Arucha: A Bracha Arucha or Matbeia Arucha refers to a lengthy blessing which either begins or ends with a blessing, or both begins and ends with a blessing, with a full paragraph in the middle, such as the blessings of Shemoneh Esrei.

Blessings which do not begin with a  blessing:[2] All blessings [including a Bracha Arucha or Matbeia Arucha] begin with the words “Baruch Ata Hashem” with exception to a blessing which is said in continuation of a previous blessing [Bracha Hasemucha Lichaverta] and a blessings of Thanks. The reason a blessing of thanks does not begin with a blessing is because its entire wording expresses thanks. Thus, for example the blessings said over rain that fell “Modim Anachnu Lach Al Kol Tipa Vetipa” does not begin with a blessing, and so applies to all blessings of this kind. An example of a Bracha Hasemucha Lichaverta is the blessing of Ahavas Olam which does not begin with a blessing being it is said after the blessing of Yotzer Oar, which counts for it as its opening blessing.

Bracha Hasmucha Lechaverta:[3] There is a dispute if a Bracha Hasemucha Lichaverta which does not need to begin with a blessing, applies even if the previous blessing is a short blessing, or only applies if the blessing which precedes it is a long blessing. Some Poskim rule that although every blessing which is said in close proximity to a previous blessing does not begin with a blessing, this only applies when a long blessing is said beforehand. However if a short, one sentence blessing is recited then the next blessing is to begin with a Bracha, just like we see by Havdala that the blessing of Hamavdil starts with Baruch despite it following the short blessing of Haeish. Others however claim that even a prior short blessings suffices in place of it needing to begin with a blessing, even though it is a short blessing. Now although by Havdala the blessing of Hamavdil begins with Baruch despite it being said after the blessing of Haeish, this is because one may say Havdala without Besamim or fire, and hence the blessings are not always said in proximity. It is likewise for this reason that the blessing of Asher Bachar Banu begins with Baruch, being that by Kerias Hatorah it is not preceded by another blessing.

Not to lengthen a short blessing or shorten a lengthy blessing:[4] The length of the blessings as coined by the Sages may not be changed. Thus, a long blessing may not be shortened, and a short blessing may not be made long. A blessing which [starts and] concludes with a blessing may not have the concluding blessing omitted, and a blessing which does not conclude with a blessing may not have a concluding blessing added [i.e. blessings on foods].

[1] See Admur 6:6; 46:4; 47:5; Rambam Brachos 1:4; Encyclopedia Talmudit Vol. 4 Erech Brachos pp. 294-295; See Torah Oar Bereishis p. 6 regarding the Halachic difference between a long blessing [begins and ends with Baruch] and short blessing

[2] Admur 6:6

[3] Admur 47:5; See Rabbeinu Tam Brachos 46; Rambam Brachos 7:10

[4] Mishneh Brachos 1:4