I need a replacement thermostat for my heat pump system my thermostat has eight wires but I keep getting a thermostat for a conventional system with less wire connections is there a way to tell the difference between the two even after asking the guy at my local home depot I still received the wrong one

First I have to ask why you are replacing your stat, and secondly what make and model system HVAC system you have?

What make and model stat did you buy?

Thermostat and Furnace Compatibility (http://homerepair.about.com/od/heatingcoolingrepair/ss/tstat_furn_coor.htm)

It's been updated so don't let the old mercury stat throw you off, just scroll through the tutorials. This is a must read!

How to Check Thermostat Compatibility with Your HVAC System (http://www.thermostatcenter.com/thermostat-compatibility/)

And this series of videos may be very helpful.

how to match a thermostat to heat system - Bing video (http://www.bing.com/videos/search?q=how+to+match+a+thermostat+to+heat+system&qpvt=how+to+match+a+thermostat+to+heat+system&view=detail&mid=581DD4D1DD6220CDA023581DD4D1DD6220CDA023&FORM=VRDGAR)

Couldn't understand your PM very well but try this, Jot all your connections down (R, Y, W for example) and make sure the new stat has all the same connections.

https://tse3.mm.bing.net/th?id=OIP.M822de1b6d60bf1ec469edb792ea05af4H0&w=213&h=164&c=7&rs=1&qlt=90&o=4&pid=1.1

Is this what you have?