There have been a few explanations for the disparity, such as...

There have been a few explanations for the disparity, such as Americans only buy EDE, the Solomon's are not paying the dividends to the TAS shareholders, the directors fees are diminishing the value of the assets, the the dividends are being used to pay for worthless mining activities, there are hidden liabilities belonging to Noble that investors don't know about.

In response the Solomon's have come out very clearly several times and said that TAS is undervalued and issued valuations based on the current EDE share price-

It couldn't be clearer. There are no hidden liabilities. Noble is a 100% owned subsidiary if TAS. The entire value of Noble's share holding is a tangible asset of TAS. The mining ventures are not being pursued, all cash raised is being used to support the Edencrete project.

There are no dividends and never have been. The directors fees are a concern, but are only a tiny proportion of the asset value. Having an independent director is something that needs to be considered now that the market cap is getting much larger.

My explanations are
1. Ignorance of the relationship to EDE and the valuation method
2. Herd behaviour. The heavily discounted share price has led to a suspicion that "the market knows something". If so, it appears "the market" must be better informed than the Solomon's
3. Relative lack of liquidity compared with EDE.

In the end logic and fundamentals will erase the difference as EDE appreciates, and the relationship with TAS becomes more widely known. Right now, TAS is the best value entry to EDE, much better than EDE options. Hopefully it will stay that way as Eden becomes derisked. But sooner or later the light bulb will come on.