Imam Ahmad Ibnul Husain Al- Bayhaqi (458 AH) has mentioned a principle which is the basis of the differences found in the salah of males and females.
The seperating factor between the laws of salah of males and females is that of concealment. A woman is commanded to do all those actions which are more concealing for her.
Raising the hands
Hafiz Nurud-din Haythami (807 AH) states:
Wail Ibn Hujr (ra) states that the Prophet (peace and blessing be upon him) said to him:
"O Ibn Hujr, when you perform salah, raise your hands till your ears while a woman should raise her hands till her chest."
Imam Abu Bakr Ibn Abi Shaybah (235 AH) narrates:
Abde Rabbih Ibn Zaytun said that he saw Ummud- Darda raising her hands parallel to her shoulders when beginning salah.
Abdullah Ibn Mas'ud (ra) states:
Should I not perform the salah of the Prophet (peace and blessings be upon him) for you? Then he performed salah and did not raise his hands except in the beginning.
Placing the hands
Allamah Abdul Hayy Lucknowi (1264-1304 AH) writes:
As for women; the jurist are unanimous that it is sunnah for them to place their hands on their bosoms
Imam Abu Dawud (275 AH) has narrated the following hadith:
Yazid Ibn Abi Habib states that the Prophet (peace and blessings be upon him) passed two women who were performing their salah. He said to them, "When you prostrate (go into sajdah), then make parts of your body touch the ground because a woman is unlike a man in these aspects
Imam Bayhaqi (458 AH) narrates the following hadith:
Abdullah Ibn Umar reports that the Prophet (peace and blessing be upon him) said:
When a woman sits during salah, she should place one thigh over the other and when she prostrates (goes into sajdah) she must attach her stomach to her thighs (ie: the stomach and thighs must touch) so that it is more concealing for her. Indeed Allah looks at her and tells the angels, "Oh My angels, bear witness that I have forgiven her."
It is reported that Ali (ra) said, "When a woman performs salah, she must practise ihtifaz (to lean on one side and rest on the posterior) and keep her thighs close together.
The Sitting Position
It is mentioned in the Musnad of Imam Abu Hanifa (150 AH):
Abdullah Ibn Umar (ra) was asked how the women performed their salah during the era of the Prophet (peace and blessings be upon him).
He replied that initially they performed tarabbu'. Then they were ordered to draw themselves close together and lean onto one side by resting on their left buttock and completely contracting themselves.
When Ibn Abbas (ra) was asked about the salah of a woman, he replied, "She must draw herself close together and lean onto one side by resting on her left buttock.
The Hanafi Madhab
'A woman should bend slightly in ruku without spreading her fingers out completely. However, she must contract herself and place her palms on her knees and bend them slightly. She must not spread out her arms as this is more concealing for her.'
'The woman will raise her hands till her shoulders (when performing takbir-e-tahrimah).'
'A female should not spread out in ruku' and sajdah while she will sit on her legs. In sajdah, she will make her stomach rest on her thighs.'
'A woman will sit on her left buttock and position her legs out to the right side.'
The Maliki Madhab
'As for a woman, she will remain contracted in all postures.'
'A male should seperate his stomach from his thighs in sajdah and his arms from his legs. As for a woman, she will completely contract herself (so that all limbs are close together)'
The Shafi'i Madhab
'A woman will join all limbs together.'
'A woman should sit in the most concealing position.'
Imam Shafi'i (204 AH) states that it is beter for a woman to completely contract herself when performing sajdah because this is more concealing for her. She must attach a great importance to concealment throughout her salah.
The Hanbali Madhab
A woman should practise sadl (ie: draw her legs out to her right side)
Imam Ahmed states that he preferred sadl.
'Concealment is preferred for a woman. It is for this reason that extending the limbs out is not mustahab for a female.'
There is no statement of any Sahabi, Tabi'i or jurist that declares the salah of males and females as the same. In fact the scholars of the Ahle Hadith sect issue fatwas according to the above mentioned ahadith.