The Similarity is that both Gurmat Bibek and Brahmanvad teaches us to discriminate but there is a major difference as well. Gurmat Bibek teaches us to discriminate based on one’s Karma whereas Brahmanvad that we know today preaches discrimination based on birth. Brahmanvad preaches that one is supreme merely because one is born in the family of Brahmans but Gurmat on the other hand preaches that irrespective of one’s family or racial background, one can rise or become holy and pure because of one’s Karma. Gurmat gives no importance to the family background. Gurmat preaches that one is good or bad only because of one's Karma and not because of one's family background.
Brahmans don’t eat from the hands of people of so called low castes because they believe that Brahmans are superior to the people of other castes whereas the Gurmat Bibeki on the other hand considers himself to be the dust of everyone’s feet. He keeps dietary Bibek not because he considers himself to be superior to others but because he is obeying the hukam (order) of the Guru.
It is the order of our Guru Sahib to associate only with Gurmat devotees and to avoid bad company. Bad company is defined as the company of such persons who are averse to Gurmat path of attaining Vaheguru. Gurmat preaches that one becomes what one’s company is. By associating with Gurmukhs, one gets inclined towards Gurmat and by associating with Manmukhs, one gets manmukhi tendencies.
It is next to impossible to become a Brahman unless one is born into a Brahman family. There is a way to become a Brahman even if one is born into a non-Brahman family but the path is very difficult to achieve. I can think of only two examples where a person was allowed to change his caste. One is Vishwamitra who was born as a Kshatriya but by following years and years of ascetic penances, he was finally accepted as a Brahm-Rishi and a Brahman. This incident occurred thousands of years ago. The most recent example of a person changing his caste is that of Shivaji Maratha who was born in a so called low caste but due to his hard work and good fortune became the ruler of his area. He wanted to be declared a Chatrapati (king) by the religious leaders but none of the religious leaders – the Brahmins - were willing to coronate him a king because he was born into a low caste family. After much effort he found some Brahmins from Kashi who using some clauses from the Hindu scriptures were able to coronate him a Chatrapati and this way changed his caste to that of a Kshatriya.
Now look at Gurmat. Gurmat is so great that anyone, irrespective of caste or race, can become a Khalsa. The conditions are same for Brahmins, Kshatriyas, Vashyas, Shudras, Muslims or whoever. Anyone who is willing to offer his head to the Satguru, can become a Khalsa. Once one is accepted as a Khalsa by Guru Sahib and is given Khande Pahul (Amrit), one becomes equal in status to all other Khalsa brothers and sisters. Two Khalsas, one from a Brahmin background and one from Shudra background hold equal status in the Khalsa Order. One gets a higher status only based on one’s Karma and not based on one’s birth. This is the difference between Gurmat and Brahmanism.
ਖਤ੍ਰੀ ਬ੍ਰਾਹਮਣ ਸੂਦ ਵੈਸ ਉਪਦੇਸੁ ਚਹੁ ਵਰਨਾ ਕਉ ਸਾਝਾ ॥ ਗੁਰਮੁਖਿ ਨਾਮੁ ਜਪੈ ਉਧਰੈ ਸੋ ਕਲਿ ਮਹਿ ਘਟਿ ਘਟਿ ਨਾਨਕ ਮਾਝਾ ॥੪॥੩॥੫੦॥
(The teaching of Naam is same for all four Varna namely Khatriya, Brahman, Shudra and Vaish. Whoever chants the Gurmukh Naam (the Naam of the house of the Guru) in Kalyuga, gets delivered; the Lord resides in the inside of all people)
I can't help but quote the previous two pankitis of this shabad. The pankitis are not related to the topic we are discussing but they are extremely lesson-giving and eye-opening:
ਬੇਦ ਕਤੇਬ ਸਿਮ੍ਰਿਤਿ ਸਭਿ ਸਾਸਤ ਇਨ੍ਹ੍ਹ ਪੜਿਆ ਮੁਕਤਿ ਨ ਹੋਈ ॥ ਏਕੁ ਅਖਰੁ ਜੋ ਗੁਰਮੁਖਿ ਜਾਪੈ ਤਿਸ ਕੀ ਨਿਰਮਲ ਸੋਈ ॥੩॥
(One cannot get salvation reading the Vedas, Katebas ( the 4 holy books of Semetic religions - Quran, Bible, Torah etc.) but one who chants the one indestructible (A-khar, without destruction) Naam through Gurmat (Gurmukh) because extremely praiseworthy).
At my workplace, many years ago, two Brahmins were my co-workers. Once, I went to the kitchen to get water and I saw them standing there ahead of me. After they used the tap, I washed the tap with soap before using it. Normally, when I wash the tap, I try to do it when no one is watching but that day I washed it in front of them. They got upset and remarked, “Arey tum apne aap ko hum se bhee baRa samajhte ho? Tum jante nahi ke hum Brahmin hain?” (You consider yourself superior than us? Don’t you know that we are Brahmins?)
I sensed haume (pride) in them and in order to break it, answered back in similar tone, “Aray Brahmin baRe honge aap ke Maharashtra mein. Hamare Punjab mein to Brahmin log, hamaare gharo mein rotiyaan banaate hain.” (Brahmins may be superior in your province of Maharashtra. In Punjab, Brahmins can be seen making rotis at our houses(in houses of normal Punjabi farmer households) during marriages and other big events)
Indeed this is true. The status of Brahmins in Punjab is not as high as other provinces where Brahmins were worshipped. This is all because of influence of Gurmat in Punjab. Still there is an effect of caste system lingering in Sikh Punjabi households but it is nearly not as bad as it is in other non-Sikh provinces of India.
Anyway, coming back to the topic, we must realize that we must follow Gurmat. If there is a similarity between a certain principle of Gurmat and Islam or Hinduism, it does not mean we should reject such Hukam of Guru Sahib. Sikhi preaches good moral character and if some other religion too preaches such character, it does not mean that we should become all defensive. If there is a similarity between a certain Gurmat Hukam and Brahmanical principle or Islamic principle, we don't need to discredit such Hukam of Guru Sahib.