Apps Making user build

[pasi_lnt]

I'm trying to make user build for one of my device. User build has
been generated but I'm not able to differentiate with eng build.
How to differentiate user build and eng build?

And one more thing when I flash user build to device phone app is
getting removed . I mean no phone app inside the device.

I have tried few below changes in .mk file(phone and dialerActivity)
but still phone app is missing in device.

LOCAL_MODULE_TAGS := user development eng

So my problems are :
How to differentiate user build and eng build?
What is the reason for phone app removal in user build and how to get
the phone app in user build ??

Any suggestion or help would be helpful for me.

Thanks

Regards,
Prasanna