Is Price Level equivalent to Inflation when looking at AD/AS and Phillips Curve graphs? Fairly straight forward, Can I assume that Price Level and Inflation are interchangeable when looking at these graphs together?

Generally, are they equivalent in Macroeconomics?
Snoram is correct. Price level is a just that, the relative level of prices. Inflation/deflation is the act of moving up/down price levels. The inflation rate is the difference in price levels from one time period to another. 

I.E. Year 1: Price level = 100 |  Year 2: Price level =105.

There was inflation in the economy (because price level increased). The inflation rate was 5%.

Another example:

I.E. Year 1: Price level = 177

In this example we do NOT know if the economy is experiencing inflation or deflation becuase we only have a single point in time and thus cannot determine the rate or direction of change.