Until 1996, deportation was divided into two categories; aliens who "entered" the United States, by evading inspection, and were caught and aliens who were caught at the border. Those caught at the border such as an airport inspection or sneaking though Canada were subject to exclusion grounds and procedures.  Aliens that were apprehended inside the United States were placed in deportation proceedings.  Those caught within the borders or the United States had greater constitutional and procedural rights than aliens in exclusion proceedings.  This gave an advantage to those aliens who had crossed the border illegally and successfully evaded inspection rather than abide by the law and seek admission at the border. 

To eliminate this advantage, in 1996 Congress replaced the term "entry" with "admission" to mean the lawful entry of an alien into the country after inspection.  Admitted aliens have greater rights than those who were  not properly admitted. In 1996 the Illegal Immigration Reform and Immigrant Responsibility Act of 1996 (IIRIRA) wad enacted, Congress changed the term "exclusion" to "inadmissibility" throughout the INA.  Even with a change in name the terms "exclusion" and "inadmissibility" are functionally equivalent. Both refer to the state of being ineligible for admission to the United States because of a failure to meet one or more of several admission criteria, or grounds of inadmissibility.    Until 1996, the distinction between the terms "exclusion" and "deportation" was an important one, pivoting on whether an alien had made an "entry" into the United States.

Nowadays, almost any violation of your status in the US can potentially result in your being placed in removal proceedings. These violations include entering the U.S. without inspection, proper documents or through fraud, improper re-entry after deportation, failure to maintain nonimmigrant status, conviction of a crime involving moral turpitude, conviction of an aggravated felony, involvement in prostitution, becoming institutionalized at public expense within 5 years of entry, becoming a public charge within 5 years of entry failure to obtain permanent residence after being granted a conditional Green Card through the marriage to a U.S. citizen or Green Card holder, narcotics addiction or violation of laws relating to controlled substance, assisting another alien to enter the United States, conviction of possession of an automatic or semi automatic weapon. A charge of deportation is usually accompanied by a document called a Notice to Appear, which requires the foreign national to appear before an immigration judge and demonstrate why he or she should not be deported and Removed form the United States.