From what i know, Artificial intelligence & machine learning are similar due to the fact, ML is a subset of AI.
In terms of which is trending and which field will continue to trend, i reckon Artificial Intelligence takes the cake for that.
Indeed ML is probably the best, however i believe all of these fields are not beginner friendly.E.g No one will hire a robotic’s engineer who doesn’t have a mechanics bachelors.
Therefore, getting starting in these field is very difficult, i’m not ruling it out thou.
Therefore, i believe yes, all the mentioned path’s are high paying. However, for a beginner or a starter its a steep slope.
Probably i’m abit biased because i have less brain cells. But I think, ML & AI peeps are big brains!!.