I haven't ordered any of the secure xplus, but I have a long history with classico, bianco, and teddy. And all three are exactly the same except for the tape panel. There is no difference in price either. The secure xplus from what I can tell is the fourth in the group. also only differing in the front tape panel, which has a much more medical look and markings to get the tapes consistently placed. They are also the same price as the bambino line, and bambino sells them right along side their other diapers.
I also have history with the bellisimo. They're the exact same construction as the above four, with a unique tape panel, but the padding has been changed. It feels very similar, but has higher capacity. They probably just sprayed in some additional SAP during manufacture, but it's definitely using the same machine and cutting die. They do cost a little more to pay for the additional SAP.
One time bambino did make a change to their teddy line, changing the tape panel to a more crinkly material, and trying out those "stretch tapes". (that were a disaster) They reverted to the original design immediately.
These have something in common with the "Totaldry Plus" also for sale on Bambino's web site. The cut and tapes are at least very similar, I believe they may be made on the same machine but use completely different padding (zero SAP?), different shell material, and of course a different tape panel. They fit me identically to the teddy etc. They also have (the same?) good standing leak guards, which is uncommon in a lower capacity diaper. Totaldry Plus are significantly cheaper.