I will start with the meaning of some terms.
Investing - The act of committing money or capital to an endeavor with the expectation of obtaining an additional income or profit. (Investopedia).
I take "profit" here in a monetary sense, not an amorphous one that might include, for example, somebody profits by doing more physical exercise or buying dentures.
Investment spending – spending which is part of an investment activity
Consumer good – something purchased (or otherwise obtained), but not an investment. There is no intent to bring about revenue, sales proceeds, or money profits.
Following common usage, consumer goods may be durable or nondurable. Investment spending may be for durable or nondurable goods. Ditto for consumer spending. (Here is the topic on Wikipedia).
Some people, like here, distinguish between industrial goods and consumer goods. I won’t use the former term. “Investment goods” will suffice in lieu of it and puts more emphasis on the intention to produce future revenue or sales proceeds or money profits.
Easy examples of an investment are purchasing stocks or bonds. A home builder laying out money to build a house for future sale is an investment and all the money he spends to do is investment spending.
Part of what inspired this post is current politics – proposals for government investing in infrastructure, e.g. repairing roads and bridges or building new ones. First consider a new toll road. A hypothetical private investor builds a road expecting to recoup the amount of money used to build it and make a profit from collecting future tolls and maybe rents from gas stations and restaurants at service plazas. Suppose instead a government did this, but future expected revenues amount to only half of the upfront cost. Then by the above meanings the cost of the new road is half investment and half purchase of a durable good.
Next suppose a government spends to repave (resurface) an existing road or build a new non-toll road. That is not an investment by the above meaning. It is far more like buying a consumer durable good such as a house to live in, or a furnace, or water heater, and so forth. In the repaving case, it's akin to spending for a new roof on your residence.
Therefore, when politicians and others talk about government investing in infrastructure, it is loose talk by the above meaning. In some cases or to some extent, it is investing. Otherwise, it is spending on a durable good.