When changing from short-haul to long-haul, differences in CRM will be related to the following considerations:
Fewer sectors per month;
Copilots will do fewer landings than captains, due to ‘heavy’ sectors;
‘Heavy’ crew will need to be included in briefings and debriefings and will require briefing during handover periods;
Less frequent visits to a particular airport;
You may be a considerable distance from a suitable en-route diversion airport;
Depending on the size of the fleet, a greater chance of flying with ‘strangers’;
Cabin crew will need to be briefed on things like high ground, remoteness from diversion airports and will need reminding in flight;
Up to half of the cabin crew may be on a break during mid-flight;
Unless you make an effort, you will not see the majority of the CC between check-in and arrival at destination;
You may depart in summer and arrive in winter (and vice-versa);
You may be much heavier than MLW for most of the flight;
You will need to pay attention to pre-flight and in-flight rest and nutrition/hydration;
There’s a greater chance of passenger problems arising; and
I could go on but I hope that you get the general idea.