Difference between Hirose U.FL and IPEX connectors

Short answer: It's a brand thing.

Long answer: All refer to micro RF coaxial connectors for 0-6Ghz applications based on the Hirose U.FL-series design.

U.FL = U.FL series from Hirose Electric Group

Specs: hirose.com/product/en/products/U.FL/

IPEX = MHF series from I-PEX Connectors

Specs: i-pex.com/Products/Micro-RF-Coax-Connector

Ya got me on IPAX...

IPX = IPX series from LightHorse Technologies

Specs: rfconnector.com/ipx-connectors.php

AMC = Amphenol Micro Coaxial connector series from Amphenol RF

Specs: amphenolrf.com/connectors/amc.html

MHF = MHF series from I-PEX Connectors

Specs: i-pex.com/Products/Micro-RF-Coax-Connector

UMCC = Ultraminiature Coax Connector and Cable Assembly Style A Series from Tyco Electronics

Specs: te.com/commerce/DocumentDelivery/DDEController?Action=showdoc&DocId=Catalog+Section%7F1307191_UMCC_Connectors%7F0307%7Fpdf%7FEnglish%7FENG_CS_1307191_UMCC_Connectors_0307.pdf%7F1307191

All claim 100% compatibility with Hirose u.fl

Yes, IPEX is a line/type of connectors made by LTI (LightHorse Technologies Inc). As @Passerby pointed out, IPEX mhf connector is the equivalent of Hiroshi U.fl (according to this website they are 100% compatible: http://www.wellshow.com/rf-connectors/mini-connector/ipex-mhf-connector/)