Is there a way to tell if my epiphone les paul is a standard or standard plus?
There sure is. Epiphone LP Standards can have a top on them, but it will have a plain old maple top. Maple, or common acer saccharum, comes in many flavors--some of which look more sexy than others. Anomalies such as flame, quilt, and birds-eye maple are prized for their beauty and often slapped atop very expensive guitars. The Epiphone Les Paul Standard Plus, however, nets you a nice flame maple top at a pretty nice price--and it ships only with flame maple from what I understand. The plain old Epiphone Les Paul Standard can have either a regular maple top or a flat paint finish with no top. So, you can tell by answering the following questions:
Does my guitar have a flat paint job where I can't see any grain on the top part of the guitar? If it doesn't, then proceed to the next question. If it does, then you have an Epiphone Les Paul Standard.
If you can see wood grain on the top of the guitar, then pick between the following pictures the one that resembles yours the closest:
If it's the picture on the left, then you have an Epiphone Les Paul Standard with a top. If it's the picture on the right, then you have an Epiphone LP Standard Plus.