What LaTeX is
A LaTeX table is a tabular environment: a column specification, ampersands between cells and double backslashes at the end of each row.
Academic papers, theses and anything typeset with LaTeX or written in Overleaf.
What PNG is
A lossless image format. Text and thin lines stay exactly as drawn, which is what a table is made of.
Slides, chat messages, issue trackers, and anywhere a table has to travel as a picture rather than as data.
What changes when you convert LaTeX to PNG
The tabular body is read, rules are dropped, and escaped characters are unescaped. Text wrapped in textbf or emph is reduced to the text itself.
The table is drawn from the data onto a canvas rather than captured from the page, so the whole thing comes out however long it is and however much of it is on screen. Column widths are measured from the content, alternating rows are shaded, and the scale is adjustable so a table for a slide or a print layout can be drawn at two or three times the size.
What carries over from LaTeX to PNG
LaTeX records 2 things about a table that PNG has no way to hold.
LaTeX can hold a value that is itself a list or an object. PNG has only flat cells, so nested values are flattened into one cell rather than being spread across columns.
Nothing in PNG records that the first row is a header. It is drawn at the top and looks like one, which is all that is left of the distinction.