I've read about the soul. What does spirit mean? Is there any difference between the soul and the spirit?
The definition of soul is:
The spiritual or immaterial part of a human being or animal, regarded as immortal.
Spirit is defined as:
The nonphysical part of a person that is the seat of emotions and character; the soul.
Both of them are two synonymous English words that have the same meaning. So, there is no difference between soul and sprit in Islam.
The soul is the "nufs" in Islam which is the union of body and the spirit "rouh". When a person dies there will be the body and the spirit that leaves the body.
Nafs refers to the soul when it is in a body and Ruh (spirit) refers to the soul when it is outside the body for example in Allah's repository before the angels blow it into the body.
When verses refer to a soul outside the body, the word RUH is used, when they refer to a soul inside the body, nafs is used.
O people of the Scripture (Christians)! Do not exceed the limits in your religion, nor say of Allah aught but the truth. The Messiah 'Îsa (jesus), son of Maryam (Mary), was (no more than) a Messenger of Allah and His Word, ("Be!" - and he was) which He bestowed on Maryam (Mary) and a spirit (Ruh ) created by Him; so believe in Allah and His Messengers. Say not: "Three (trinity)!" Cease! (it is) better for you. For Allah is (the only) One Ilah (God), glory be to Him (Far Exalted is He) above having a son. To Him belongs all that is in the heavens and all that is in the earth. And Allah is All-Sufficient as a Disposer of affairs. (سورة النساء, An-Nisaa, Chapter #4, Verse #171)
Narrated 'Abdullah bin Mus'ud: Allah's Apostle (SAWS), the true and truly inspired said, "(The matter of the Creation of) a human being is put together in the womb of the mother in forty days, and then he becomes a clot of thick blood for a similar period, and then a piece of flesh for a similar period. Then Allah sends an angel who is ordered to write four things. He is ordered to write down his (i.e. the new creature's) deeds, his livelihood, his (date of) death, and whether he will be blessed or wretched (in religion). Then the soul is breathed into him. So, a man amongst you may do (good deeds till there is only a cubit between him and Paradise and then what has been written for him decides his behavior and he starts doing (evil) deeds characteristic of the people of the (Hell) Fire. And similarly a man amongst you may do (evil) deeds till there is only a cubit between him and the (Hell) Fire, and then what has been written for him decides his behavior, and he starts doing deeds characteristic of the people of Paradise." (Sahih Bukhari, Book #54, Hadith #430)