I'll try to answer this best I can, this will be longer than it needs to be, but I think putting it down in one post will save time later.
First, base defense designations of a common front like that are meaningless in today's game because the concept of a base defense is kinda fading away. That designation made sense when teams passed the ball more on specific downs, and therefore used specific personnel in specific situations. In today's game, you may never leave nickel or dime personnel for the entire game, and teams are just as likely to use 3 or 4 WR on first down as they are third down. Regardless of defense, you're likely to see 4 rushers and 7 in coverage because of min/max basic defensive theory principles. This has meant that some descriptors we've always used, like FS/SS are no longer relevant. OLB/DE is a messy concept entirely these days. In general usage its often better to just describe them as edge players. Specific teams will use specific terms like Cat, Dog, Monkey, Squirrel, whatever.
When I refer to scheme, it is front agnostic, for the most part. Scheme should be described as the general rules and philosophies describing a specific defense. Things like Strength Declaration, Handling Motion/Shifts, Gap Philosophy, Coverage Philosophy, etc.
To answer the question: Yes and No. If you're switching to Pelini's defense, regardless of what you're switching from, it's probably less complicated to switch. Pelini's defense is a pretty quick install, doesn't take long. In general, I wouldn't ever make a coaching decision based on this particular question. Football is football. The biggest initial hurdle is vocabulary because everyone uses different words and one guys word is another thing in another guys defense. After that, its mostly tweaking things to accommodate for philosophy and that's done very quickly if the players already know the basic ideas.
