If you are familiar with Cisco IOS and have been asked to look at some Juniper hardware you will be aware of the differences between Junos and IOS.
Junos have provided this pretty good CBT course entitled Junos as a Second Language – you will need a login to the Juniper site but you can register for free.
Another great thing about this course is you can pickup where you left if you do not make it through or just choose the sections that are relevant to you.
Juniper have done a great job here on explaining the differences between IOS and Junos and for anyone taking the JNCIA this is great learning tool