x = x-axis variable, y = y-axis variable, and z = size of the bubble variable.
A scatterplot displays the values of a dataset with two numeric variables. each data point is plotted on a grid, where the x-axis indicates one variable, and the y-axis indicates another variable. Oftentimes a line of best fit is drawn to show general trends in the data and the relationship between the variables.
For additional information, check out https://www.data-to-viz.com/graph/scatter.html
Example of a scatterplots would be these hypothetical ones from https://datavizcatalogue.com/methods/scatterplot.html
A bubble chart is similar to a scatterplot in the fact that two variables are mapped out along the x- and y- axis. What makes a bubble chart unique is that it adds a third variable by altering the size of the dots to indicate a numeric value.
Here is an example of a bubble chart from https://visage.co/data-visualization-101-bubble-charts/