Farab border crossing
There are technically 3 border crossings between Uzbekistan and Turkmenistan: Khojeli (near Nukus), Konye-Urgench (near Khiva) and Farab (near Bukhara/Turkmenabat). When you apply for your visa, you will have to mention which border crossing you hope to use. You may or may not get this border crossing. The entry/exit points are usually printed on the visa itself.