What MediaWiki is
MediaWiki table markup opens with {| and a class, marks headers with an exclamation mark and rows with |-.
Wikipedia editors and anyone running a MediaWiki install.
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 changes when you convert MediaWiki to PDF
Both cell styles are read: one cell per line, and several on a line separated by exclamation marks or double pipes, which is the form most Wikipedia tables use. Cell attributes before a single pipe are dropped, since style="text-align:right" is presentation rather than data. Wiki links come through as their display text, so [[France|the French Republic]] arrives as the French Republic, and reference markers are removed.
The table is drawn into a paginated document with the header repeated on every page, so a long table stays readable past page one. Page size, orientation and font size are all adjustable.
What carries over from MediaWiki to PDF
MediaWiki records 3 things about a table that PDF has no way to hold.
MediaWiki can hold a value that is itself a list or an object. PDF has only flat cells, so nested values are flattened into one cell rather than being spread across columns.
Nothing in PDF 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.
PDF is the end of the line for this data. Reading the table back out of it is a separate and much harder problem than writing it, so keep the MediaWiki if you will need the values again.