Here are some of the changes:
Bars to Re-Entry. A person who is in the US in unauthorized status for 12 or more consecutive months beginning April 1, 1997 and who leaves the US will be barred from admission to the US for 10 years. People who were here in unauthorized status for 6 consecutive months and then leave can be barred from admission for 3 years.
INA Section 245i, Adjustment of Status in the US. The law which allowed people to apply for a green card in the US (adjustment of status) even if they overstayed, worked without permission, or entered without inspection, has ended except for some savings clauses which will permit those who had Immigration petitions or Labor Certificate applications filed by January 14, 1998 to continue to adjust status (apply for a green card) in the US under Section 245i. Others who are out-of-status will have to apply for the green card outside the US and if they have been in the US in unauthorized status for more than 6 months, they can be barred from re-rentry for 3 years. (10 years if in unauthorized status for over 1 year). There are exceptions to every rule including this one. For example, it does not apply to immediate relatives of US citizens who entered with inspection and to some others.
With Section 245i no longer in effect, an unauthorized person cannot apply for a Diversity Lottery visa in the US. If they go back home to apply, they are subject to the 3 year and 10 year bars to re-entry. It seems that the Lottery is no longer a possibility for those in the US in unauthorized status for over 6 months.