Is the Retention Phase for Invisalign Different Than Traditional Braces?

Recent research has shown  that wearing retainers at night is just as effective as wearing them all the time. Other research shows that the invisible retainers hold better and there is better compliance with them.

Yes, they are for a life time. Some can wear them one or two nights a week, others every night.

If I make a fixed retainer ( I don't think any are strictly permanent) I still make a clear retainer to be work over the fixed retainer in case the fixed retainer comes off. When the fixed retainer comes off the teeth will move. That is the reason for the invisible retainer

Orthodontic retention is a tricky subject, we all do things differently. 

Teeth relapse because they usually want to go back to where they came from.  Retention is almost always needed.  We all have busy lives so i believe that fixed retention works best for most of us especially on lower teeth.  These fixed retainers may be in the form of a metal wire bonded to the back of the teeth or a tooth coloured wire.

For the top teeth we either use a wire (same as bottom teeth) or a clear essix or vivera type retainer that is worn primarily at night. 

Orthodontic retention is one of the most important aspects in orthodontic treatment but one of the least-discussed.  Retention is unique to every individual.  For instance, I had conventional orthodontic treatment with braces and Hawley retainers made for the retention phase which I wore at night religiously for several years.  I haven't worn retainers for 20 years now, but I'm still technically in a retention phase (as every orthodontic patient is, for life, once the treatment phase is complete).  I've been very lucky not to have experienced any orthodontic relapse.

When I finish a ClearCorrect or Invisalign case, I instruct the patient to wear his/her retainers at night.  If he/she finds that the retainers are very tight when applied each night, then the retainers may need to be worn during the day.  Usually, this is a non-issue.  Most people will be able to maintain retention by wearing retainers at night.