A motion to dismiss means that you want to end the case without reward. A summary judgement motion means that you give up and the person who filed suit against you gets whatever they sued to get.

They are completely different things. In a motion to dismiss a party is asking the court to completely dismiss the case because the complaintant's case (usually the Plaintiff) is invalid for one reason or another. The court may dismiss the case with prejudice (meaning the complaintant cannot ever sue the respondent again for the same thing) or without prejudice (meaning the complaintant can sue the respondent again for the same thing). EITHER party may file a motion for summary judgment (not just a defendant). In a motion for summary judgment the party making the motion is claiming that the evidence is so overwhelmingly in their favor that they should automatically win the case without a trial.

The most common motion to dismiss is a "Motion to Dismiss for Failure to State a Claim Upon Which Relief Can be Granted." This is true in Federal court cases and most states (some states like California use something else called a Demurrer which works pretty much the same way. The essence of this motion is that the person making it (usually the defendant in a civil case) says to the court - if we hypothesize that everything the plaintiff says is true actually is true, there is still no case. For example in a negligence case you need to show that the plaintiff was harmed by the negligent action that was cause and proximately caused by the defendant. If the plaintiff's pleading doesn't show any harm or any negligence or any causation, then that is grounds for dismissal. In essence any motion to dismiss is asking the court just to drop the case because something critical to the process wasn't said or done. In most cases after a motion to dismiss is granted, the party against whom it was granted can fix the problem and file the lawsuit again. A summary judgment motion is very different. It is like a trial but one that occurs only on the passing of paper between the parties. It usually occurs when the entire between parties turns on a purely legal issue. For example let's say a contract on its face is ambiguous, the case in our hypothetical turns on whether we can admit outside evidence. The parties submit briefs (written arguments) and the court rules that, as a matter of law, outside evidence cannot be admitted. The court then grants summary judgement and the case has been fully adjudicated. This is just one of hundreds of possible scenarios. The simple answer is that a motion to dismiss is based on some procedural matter and is often fixable. A motion for summary judgment is a substantive ruling and has the same legal effect as if a trial had occurred.