You're right! The difference is in the call rates and account page interface.
To compare the two nakamobile/chilisim offers:
swissmobile has only one number (+447509... jersey) attached to it. Secondary numbers have been disabled (and fair enough, they are really confusing, which makes customer care more expensive). Outgoing calls are around 0.14 CHF/min. 1Gb data roaming in the EU for 30 days cost 19.90 CHF.
pilot-call also has a jersey number attached as primary number, but an additional number for free ( choice from US, german, spanish or polish number). More than one secondary number costs €1/month. If a secondary number is not used for 30 days it is deactivated. In comparison to Toggle mobile there is an important difference: any secondary number can be set as caller id . The call rates for pilot-call are a bit lower: 0.10 €/min. 1Gb data is more expensive with pilot-call at 27.90 €.
Other than the rates and packages there is really not much difference between the two offers. Even the interface is very very similar. I've tested both extensively and found them quite reliable, good voice quality, no serious problems encountered. I've never tried the swissmobile customer service, so can only say that from my experience pilot-call has a very fast and competent service that took time to answer my questions about the service in detail.
Maybe one more interesting fact: Pilot-call and swissmobile (this feature is not advertised for swissmobile, but it still works!) both come with a SIP account that can be used to make voip calls to mobiles and landlines from your smartphone (using for example sessionchat, zoiper, or any of countless other apps). The login details are your number without the + prefix and the password is your account password. As server you put sip.chilisim.com (both swissmobile and pilot-call and probably all other nakamobile/chilisim offers). Here too is a small difference in call rate: landlines can be called for 0.016 €/min and mobiles for 0.029 €/min. The swissmobile SIP rates are the same, except in chf/min. (The swissmobile SIP rates can be found on their website: they are the same as the forwarding call rates, as forwarding is also done over SIP)
Fazit: if you would like to forward a swiss number to your roaming sim, pilot-call is the better option, as calls to a US mobile are way cheaper than to a Jersey number (with the new SALT prepay it's 3rp/min to forward to US number). If cheaper data roaming is more important to you than swiss mobile is the better option (and don't forget: you can make cheap voip calls over 3G!)
The only thing that's really missing for all nakamobile sims is the swiss number option. Unfortunately this will probably not come very soon either as I was told by customer service, but I don't know the reason.