Netscape and Mozilla On The Same System

Preface:
Mozilla is an open-source development project created by Netscape. The goal was to make a internet suite like Communicator with performance, portability, and standards compliance in mind. When the Netscape marketing team thought the Mozilla code was mature enough, they released their own Netscape branded, customized, end-user version of the Mozilla code in the form of Netscape 6. All versions above that use the Mozilla codebase.

For an extended explanation, read this document's companion piece, Understanding the Relationship and History Between Mozilla and Netscape.

Netscape and Mozilla On The Same System:
Netscape and Mozilla are two separate programs. You can install both applications on your system, and use them simultaneously. You can keep one of them installed, while you are trying the other.

However;
they do use the same profile registry, so if you install Mozilla while Netscape is installed, Mozilla will use your Netscape profile (and vice versa, if you install Netscape while Mozilla is installed). Sharing a profile between the two programs causes corruption with preferences.

So;
if you plan on keeping one while you try the other, it's best to create a separate profile, so that you have two: one exclusively for Netscape, and another exclusively for Mozilla. If you do not plan on using one of them at all after you install the other, just let the newly installed program use the profile the other one was using.

Note: If you plan on creating a second profile, it's best to create it, prior to installing the other program. This is because both installers automatically launche the program at the end of the install process. If there is one profile (Netscape profile), Mozilla will automatically use that profile, thus corrupting that profile's preferences. If there is one profile (Mozilla profile), Netscape will automatically use that profile, thus corrupting that profile's preferences. If there is more than one profile in existence, you will get the profile manager, when the program first starts. This allows you to prevent Mozilla from automatically opening your Netscape profile; or prevent Netscape from automatically opening your Mozilla profile. Again, this paragraph only applies if you plan to keeping both programs installed.

Alternatively, you can also completely separate the Mozilla and Netscape profile registry by following the instructions laid out in #33 of the Netscape UFAQ.