Auto-organization of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mrow><mml:mn>2</mml:mn><mml:mi>H</mml:mi><mml:mo>|</mml:mo><mml:mn>3</mml:mn><mml:mi>R</mml:mi></mml:mrow></mml:math> lateral boundaries in bilayer <mml:math xmlns:mml

Small changes in the structure of thin bidimensional transition metal dichalcogenides (TMDs) can radically alter the overall material properties. Here, we investigate the epitaxial self-organized boundary between two tungsten diselenide domains obtained by chemical vapor deposition: the AB ferroelectric bilayer (noncentrosymmetric, <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"><a:mrow><a:mn>3</a:mn><a:mi>R</a:mi></a:mrow></a:math>-like) and the conventional AA' bilayer (centrosymmetric, <b:math xmlns:b="http://www.w3.org/1998/Math/MathML"><b:mrow><b:mn>2</b:mn><b:mi>H</b:mi></b:mrow></b:math>). Several tools are used to isolate and confirm the different polytype signatures, such as micro-Raman, second harmonic generation (SHG) and photoluminescence. Transmission electron microscopy is found to bring complementary information to Raman and SHG in the polytype determination. Finally, we resolve and index a particular sawtooth structure in the experimental <c:math xmlns:c="http://www.w3.org/1998/Math/MathML"><c:mrow><c:mn>2</c:mn><c:mi>H</c:mi><c:mo>|</c:mo><c:mrow><c:mn>3</c:mn><c:mi>R</c:mi></c:mrow></c:mrow></c:math> boundary wall, whose origin is linked to particular twin boundaries observed in other TMDs.