Compatibilty of WinZip&PKZip

Hi,
Are there any compatibilty issues if someone zipped a file with winzip and sent it to another person who has pkzip or vice versa and wants to unzip the file. Any suggestions or good resources would be appreciated. A client said her boss sent her or gave her a file and they have different zip programs and she can’t open it. she said that there are instructions about going into dos and opening it there but she still has not been able to open it.
Have A Safe Day
Mark