What are some pragmatic differences between Algerian society and American/ English society regarding politeness?

If in terms of politeness, you mean the differences in etiquette between the two cultures, I can answer your question from that angle.
The differences in culture largely stem from the fact that Algeria is an Islamic country; more than 90% of Algerians are Sunni Muslims. There are minority Christian and Jewish groups, but these form only about 1-2% of the Algerian population. Algerian societal interactions are divided along gender lines. Public displays of affection are more common among members of the same gender. Meanwhile, effusive displays of emotion between men and women are largely frowned upon.
In American culture, members of both genders may openly show displays of affection, especially in an informal setting. In business settings, however, public displays of affection are considered rude. Interestingly, this is true, whether we are talking about Algerian or American culture.
In Algeria, conversational topics such as sex, religion, and politics are carefully avoided. Algerians are especially sensitive about issues surrounding Islamic fundamentalism/terrorism and will be offended if visitors bring up these topics, whether in an informal or formal setting. In American culture, people usually avoid these subjects, unless the host indicates his/her openness to discussing them.
There is one important difference, however, between the two cultures. Sometimes, in an informal setting, Americans may reveal some very personal information about themselves in the midst of conversation. Algerians may find this habit positively shocking and react accordingly. In business settings, however, topics such as sex, religion, and politics are considered taboo in both Algerian and American culture. 
In the area of gender equality, Americans view both men and women as equals. American women participate at all levels of society; they may be CEOs, homemakers, or public servants, as they choose. In contrast, Algerian women must follow a strict code of conduct for women; formally, they are forbidden to participate in political activities and cannot enter areas apportioned to men only.
For more information about pragmatic etiquette differences between Algerian and American society, please refer to the excellent links below.
 
 
https://www.international.gc.ca/cil-cai/country_insights-apercus_pays/ci-ic_dz.aspx?lang=eng