I do not agree with your definition. The main reason is that there would be no investors since to be branded an investor one has to cover all markets (all markets in all countries, including the copper market in Bangladesh, rice market in Chile and stock market in Zimbabwe). I also think that even an investor do try to outperform the market with his market knowledge that is based on research.

I do agree that the that the instrument has nothing to do with speculation vs investment. A portfolio of 100% T-bills can speculating in that other markets will fall but also an investment by an extremely risk-averse investor..

The difference can not be easily defined as there is no clear cut between what is investment and what is speculation. It is much up to the intention of the trader and the purpose of the trade.