Scott Manley does a pretty good explanation of these changes in his most recent video: https://youtu.be/upgg_svZRr4
Cancellation of the Exploration Upper Stage and Block IB upgrade for SLS rocket
Artemis II and Artemis III missions will use the SLS rocket with existing upper stage
Artemis IV, V (and any additional missions, should there be) will use a “standardized” upper stage
Artemis III will no longer land on the Moon; rather Orion will launch on SLS and dock with Starship and/or Blue Moon landers in low-Earth orbit
Artemis IV is now the first lunar landing mission
NASA will seek to fly Artemis missions annually, starting with Artemis III in “mid” 2027, followed by at least one lunar landing in 2028
NASA is working with SpaceX and Blue Origin to accelerate their development of commercial lunar landers for Artemis IV and beyond



