Migration is defined as the movement of people from one area to another.
It is initially what happened when Homo Sapiens came into being in Africa. They spread around the world as explorers, always wanting to see what was across the river or over the hill. Migration has taken place over time, it hasn’t stopped. People moved because they were curious, their food moved (animals), their crops didn’t grow, the climate changed with ice age, there were floods. These days the cause of migration is more varied: floods, earthquakes, volcano eruptions, famine, armed conflicts, persecution over faith or sex, armed conflict and lately, human induced climate change. People move because they want/need a better life.
Immigration is about people moving to areas where they have “no rights”. This is down to groups of people (tribes if you will) creating artificial constructs called nations or countries. Where a legal jurisdiction has been constructed based on people being united on the basis of culture or beliefs. And this is where the problem of migrants comes in. If it wasn’t for these legal artificial constructs there wouldn’t be a problem. But these nations or countries want to protect their “rights” and stop people moving about at will. Most of these restrictions fail to acknowledge what is happening in the world and the issue of “migrants” will just increase over time. This will especially be the case when human induced climate change forces people to move from one area to another. It used to happen all the time before these artificial constructs came into being.
Now you get people wanting to “protect their borders”. In the UK however, the borders have never been protected. The UK is a group of islands. It would take a lot of effort to monitor every single bit of the coastline. Those that advocate this “control” are not being realistic. Land locked countries might be able to monitor their borders more easily. But, if huge numbers of people mass on the border can they really stop them? Should they when the cause is changes in climate making life where they were untenable. Should all countries accept the inevitable.
Migration is a fact of life on this planet.