Procedurally they are very different. A lawsuit is usually begun with the filing of a complaint. A motion for summary judgment claims that the facts are not disputed and that a party is entitled to a judgment as a matter of law.
A lawsuit describes legal proceedings which (hopefully) result in resolution of a dispute or grant of a request. There are many types of motions within a lawsuit and a motion for summary judgment is a request for a judgment without trial because there are no disputes as to the critical facts. This motion substitutes for a trial so testimony is done via declarations of witnesses/parties. The judge reads the declarations, reviews the legal argument documents filed by the parties and (sometimes) comes up with a ruling. Sometimes the ruling is that not all the critical facts have been determined so that a trial is needed anyway. So a lawsuit and motion for summary judgment are not at all the same.
Lysbeth Goodman is an attorney licensed in the state and federal courts of California. This answer is for general information only and does not create an attorney client relationship between Lysbeth Goodman and any other person. You should schedule a consultation with an attorney to discuss the specifics of your legal issues.
In either case, if you have received notice of an impending suit or a motion for SJ, you may consider contacting the Passaic county lawyers aid program (http://lawyers.justia.com/firm/passaic-county-legal-aid-society-volunteer-lawyers-program-9424) to assist you with your issue.