Hell is the worst place to reside in as mentioned every where in Quran. We seek Allah's refuge from the hell fire and its torments. According to the levels and degrees of hell, it is written in Quran that hypocrites will be thrown down to the lowest level of hell which is the worst place of all. As for the level of hell where lightest punishment will be given to the people, it is mentioned in a sahih hadith about the paternal uncle of Prophet Muhammad pbuh;
“The least severely punished of the people of Hell will be a man who has two shoes and shoelaces of Fire – according to another version: two live coals will be placed on the soles of his feet – because of which his brains will boil as a pot boils. He will not think that anyone is being punished more severely than him, but he will be the one who is punished most lightly.” (al-Bukhaari, 6562; Muslim, 212)
As for the levels of heaven, it is mentioned in ahadith that the highest level of heaven is called jannah-tul-firdous. Prophet Muhammad pbuh has told us that whenever we ask for jannah, we should ask for jannah tul firdous for it is the highest heaven. As for the number of the levels of jannah, there is a hadith which indicates that there are as many levels of heaven as the number of the verses of Quran;
Prophet (pbuh) said: “It will be said to the companion of the Qur’aan: ‘Recite and rise in status as you used to recite in the world, and your position will be at the last verse you recite.’” Narrated by Abu Dawood, 1646; al-Tirmidhi, 2914; classed as saheeh by al-Albaani in Saheeh Abi Dawood.
There is another hadith which indicates the levels of paradise according to the deeds of people.
It was narrated from Abu Sa’eed al-Khudri (ra) that the Prophet (pbuh) said: “The people of Paradise will be able to see the people in the apartments above them as you see the shining stars on the horizon in the east and the west, because of the differences in their status.” They said: “O Messenger of Allaah, is that the status of the Prophets which no one else will reach besides them?” He said: “No, by the One in Whose hand is my soul, they are men who had faith in Allaah and believed in the Messengers.” Narrated by al-Bukhaari, 2082; Muslim, 2831.
There is another hadith which indicates the degrees of paradise according to the deeds;
It was narrated that Abu Hurayrah (ra) said: The Messenger of Allaah (pbuh) said: “In Paradise there are one hundred degrees which Allaah has prepared for those who strive in jihad for the sake of Allaah. The distance between each two degrees is like the distance between the heavens and the earth.” Narrated by al-Bukhaari, 2637.
Therefore, levels of hell and heaven are different according to the level of the deeds of the people. It is not right to say that there are seven heavens or seven hells. But heaven and hell are one each. They have degrees for every person according to the level of his good/bad deeds. And Allah knows the best.