What is nav+ vs nautic?

I've noticed on the lowrance elite 4 hid chart plotting fish finder is says nautic pro cartography and the elite 5 says nav+ cartography... What's the difference? Do they both have gps? Do they both show US lakes? Elite 4 hdi is on sale right now under 180$ and elite 5 is around 399$. What do you recommend?

Dude!  Google!

Insight is cartographic software by Navico (Lowrance).  Navionics+ (Nav+) is cartographic software from Navionics.  Navionics+ is the better product, in my opinion.

Both do lakes, but neither do them in great detail.  Adequate, not great.

Insight: http://www.lowrance.com/en-US/Products/Mapping/Nautic-Insight-Pro-v15-1.aspx

Navionics+: http://www.navionics.com/en/navionics-plus-2

Yep, both have built-in (internal) GPS - the maps don't work without it.

Read the SPECS page here:

Elite-4 HDI: http://www.westmarine.com/buy/lowrance--elite-4-hdi-chartplotter-fishfinder-with-83-200-455-800khz-transducer-nautic-pro-cartography--17030388?cm_mmc=PS-_-Google-_-Shopping_PLAs-_-17030388&adpos=1o2&creative=78602819764&device=c&matchtype=&network=g&gclid=CM6xz7rz98sCFdgSgQodR0YAgA

Elite-5 CHIRP: http://www.westmarine.com/buy/lowrance--elite-5-chirp-fishfinder-chartplotter-with-83-200-455-800khz-transducer-nav-cartography--15631542

THEY ARE VERY DIFFERENT.  One is bigger and includes CHIRP and HDI, the other is smaller and does not include CHIRP.  CHIRP is a matter of personal opinion.  It is claimed to reduce interference from other nearby sonar units and from powerboat propeller noise - if that's important to you, then you have the answer to CHIRP/no CHIRP.

Either of them will do the job and do it well.  What boat are you going to put it on?  Can you mount it close enough to see the smaller screen or will it be easier to see the bigger screen?  Do you have room for the larger display unit of the Elite-5 or will the Elite-4 better fit the available space?  Do you have the budget for a $350 finder or for the $180 unit?  (The costs of accessories to mount and power the unit are not trivial)

You have to answer those kinds of questions yourself.

If you primarily want to fish lakes, you might want to look for a unit packaged with a different map card.  The two map cards you are asking about are biased toward coastal waters, so won't have much detail on fresh water.  If you primarily want to fish lakes, there are probably better, more detailed cards out there.  The trade-off is that those cards won't have as much detail on coastal waters.  I don't have a recommendation on a good card for lakes, sorry!