What is the difference between expansionism and interventionism?

The differerence is i need the points and you have them

Imperialism
◆ The word imperialism originates from the Latin word for empire imperium, which denotes supreme command or authority. It was first originally coined in France in the 1830s to refer to an enthusiast of the former Napoleonic empire.
◆ The term is popularly used to trace the rapid colonization policies of European countries during the eighteen and nineteenth centuries. Politically, the term refers to aggressively channelize annexation of sovereignty and territorial dominion over distant overseas territories through military conquests. It also refers to collateral political or economic control of powerful nations over weaker nations.
◆The greed to subject new territories under one rule has always motivated the conquest of foreign lands; it would also mean the monopolization of raw materials from the foreign lands for monetary gains.

Expansionism
◆The industrial revolution caused extensive expansion policies of the European countries over the Asian and African continents to gain new territories for raw materialistic gains. The need for a constantly expanding market for products caused expansionism over the entire surface of the globe; thus, the means to gain economically can be termed as 'Capitalist Expansionism'.
◆An economic expansion is marked by increased production with labor gains and exploitation of resources from the weaker nations. The associations between mercantile capital, empire building, and colonial ventures had already been secured by the late eighteenth century. Capital inducted in the triangular trade between England, Africa, and the Caribbean region had a heavy impact on New World Iberian colonies. The African slave trade, for example, provided labor force for Brazilian and Caribbean sugar plantations that produced sugar for the western Europe and North America markets. Colonial capitalism was indeed a sign of global finance capitalism.

Primary sources are usually  more accurate and are written by someone who experienced it or witnessed it. secondary sources are those who heard of it after the fact that can lose details and or twist the event in a light that benefits them.