A Word document is built from structured elements, paragraphs, tables, headings, that the format explicitly tracks. A PDF is built from precisely positioned marks on a page, this text sits at these coordinates, this line is drawn here, with no inherent record of which marks belong to the same paragraph, table cell, or column. Converting PDF to Word means reconstructing that structure from visual layout alone, which works well for simple documents and badly for complex ones, and understanding why explains most conversion problems before they happen.
Why tables are the hardest part
A PDF table isn't really a table in any structural sense, it's just text positioned in a grid pattern, sometimes with visible lines, sometimes without. A converter has to infer from spacing and alignment which text belongs in which cell, and that inference breaks down on tables with merged cells, inconsistent spacing, or no visible gridlines at all. If tabular data is the main thing you need out of a PDF, it's often more reliable to extract it directly with the PDF Table Extractor, which is purpose-built for reconstructing rows and columns, rather than converting the whole page to Word and fixing the table by hand.
Multi-column layouts and reading order
A two- or three-column PDF page (common in newsletters, academic papers, and brochures) stores text in the order it was placed during creation, which doesn't always match the order a human would read the columns in. A converter reading left-to-right, top-to-bottom across the whole page can jumble column content together, mixing sentences from column one with column two mid-paragraph. This is a genuinely hard problem for any converter to solve perfectly, since the PDF format itself doesn't record which text belongs to which visual column.
Fonts and why the converted document looks different
If a PDF uses a font that isn't installed on the system doing the conversion (or isn't embedded in the PDF itself), the converter substitutes a similar-looking font, which shifts line breaks, spacing, and sometimes page count. Embedded fonts convert most reliably since the exact glyph shapes travel with the document. Running PDF to Word on a document with standard fonts (Arial, Times New Roman, Calibri) in a single-column layout typically produces a near-perfect conversion, while a design-heavy PDF with custom fonts and complex layout should be expected to need manual formatting fixes afterward, that's a structural limitation of the conversion, not a sign the tool did something wrong.