Title IX investigations and proceedings are relatively informal. The worst outcome possible for the “accused” is being kicked out of college. The accused does not have most of the procedural rights he might have in court, including significantly such things as the right to a qualified, impartial judge, the right to a jury, the right to be represented by counsel, discovery rights against his accuser, the right to be considered innocent unless proven guilty beyond reasonable doubt, and the right to have his counsel cross-examine witnesses and present his own witnesses.
Criminal investigations are handled by the police, and prosecutions are done in court. The accused has many, many more procedural rights, including those listed above, and the police have much more investigative power, too.
The accused can be arrested prior to trial. and may be sent to prison if found guilty.
Civil lawsuits are mostly about money damages, although they can also include protective injunctions. They are carried out by the victim and her family, usually, not public prosecutors. The accused’s procedural rights are not as strong as in a criminal case, but still pretty strong.