They are absolutely not the same.
I've looked at the chemistry here in some detail.
Imunovir contains 3 compounds.
You can use the molecular weights and molar ratios to calculate how much of each is present.
500 mg of imunovir is equivalent to;
135.6mg of inosine
156.4mg of DMAIP (Dimethylaminoisopropanol)
208.0mg of PABA (para amino benzoic acid)
If you take, for example, 3 imunovir, you will be taking about 405mg of inosine, less than in ONE 500mg inosine pill. Taking them in the same amounts (same number of pills) will cause a much, much greater increase in serum uric acid with the inosine, and could precipitate gout.
The DMAIP is a rather mysterious chemical. I have not found it used anywhere else for human consumption. The patents for imunovir suggest that amino alcohols could be used, such as DMAE (dimethylaminoethanol). This is available as a supplement, but we have no data on whether or not it helps or is safe in ME.
PABA may be inert. Bacteria use PABA to make folic acid I believe (off the top of my head). I'm not sure what value it has in imunovir or if it's only added to stabilize the amino alcohol.
Studies on DMAE in humans (which is different) have shown it makes skin look younger - but it may do this by somehow increasing size of intracellular vacuoles, which may not be good for you. I'm not really sure. I think some of the activities of imunovir may be on intracellular phagosomes, but it requires further study.
The most important point here is that imunovir and inosine are not the same thing, and they cannot be substituted milligram for milligram. 1 500mg inosine pill is between 3 and 4 imunovir pills in terms of inosine content.
I think the DMAIP is biologically active and important. I'm not sure how yet. It's one of the things I looked at at one point but have no firm conclusions on.
I have had generally excellent results with imunovir. It's not clear why.