What PDF is
PDF describes a page: glyphs at coordinates, not rows and columns. A table in a PDF is a visual arrangement, not a data structure.
Reports, invoices, statements and anything sent to be read rather than processed.
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 changes when you convert PDF to LaTeX
Every character in a text-based PDF carries its position on the page. Characters sharing a baseline are one row. Columns are found from the vertical strips no character ever occupies, which is why extraction works cleanly on a document laid out with spacing and badly on one laid out with ruled lines. A header repeated at the top of each page is detected and dropped rather than landing in the middle of the data.
Rules are drawn with booktabs by default, which is what most journal templates expect. The characters LaTeX treats as special, & % $ # _ { }, are escaped so a value like 50% compiles instead of ending the line.
What carries over from PDF to LaTeX
One property of the PDF has no home in LaTeX, and it is worth knowing which before you convert.
A line break inside a cell ends the row in LaTeX, so line breaks are replaced rather than carried through.
LaTeX marks its header cells differently from its data cells, so the first row is written with that marker.