In-Degree (how many other people who follower SCOREProject or ukoer also follow the person represented by the bubble); and
Followers count (how many people follower the person represented by the node
Clicking on 'Grouped' button lets you see how bubble/people follow either the SCOREProject, UKOER or both. By switching between betweeness, degree and followers we can visually spot a couple of things:
Betweenness Centrality: SCOREProject has 3 well connected intercommunity bubbles @GdnHigherEd, @gconole and @A_L_T. UKOER has the SCOREProject following them which unsurprisingly makes them a great bridge to the SCOREProject community (if you are wondering where UKOER is as they don't follow SCOREProject they don't appear.
In-Degree: Switching to In-Degree we can visually see that the overall volume of the UKOER group grows more despite the SCOREProject bubble in this group decreasing substantially. This suggests to me that the UKOER following is more interconnected
Followers count: Here we see SCOREProject is the biggest winner thanks to being followed by @douglasi who has over 300,000 followers. So whilst SCOREProject is followed by less people than UKOER it has a potential greater reach if @douglasi ever retweeted a message.
Sticking with the grouped bubble view we can see different colour grouping within the clusters for SCOREProject, UKOER and both. The most noticeable being light green used to identify Group 4 which has 115 people people following SCOREProject compared to 59 following UKOER. The groupings are created using community structure detection algorithm proposed Joerg Reichardt and Stefan Bornholdt. To give a sense of who these sub-groups might represent individual wordclouds have been generated based on the individual Twitter profile descriptions. Clicking on a word within these clouds filters the table. So for example you can explore who has used the term manager in their twitter profile (I have to say the update isn't instant but it'll get there.