Hello
There are lot of difference bwteen cisco and juniper.
Cisco using monolithic operating system Ios and juniper using modular os Junos based on free BSD.So architectural wise its different.
According to my knowledge CISCO is more user friendly than juniper. Junos hierarchy is little difficult for newbies .
Cisco is, for many, still the first name in networking: they were the first into the enterprise networking world and are still the majority seller when it comes to units sold for enterprise and small business networking due to the versatility and feature set.
Regards,
Christian