It never ceases to amaze me how different looks can be created with mostly the same clothing pieces - I think that might be one of my favorite things about fashion. Sometimes I play around while I'm taking outfit photos to see which changes affect the overall look the most. Often, changing just one piece doesn't really make a notable difference (I'll be posting a look that demonstrates this soon - just changing a skirt to pants didn't measurably alter the overall feel of the outfit). In this case, however, the only change made in these two outfits, was changing out the coat - from a denim jacket to a trench coat. Doesn't it look like more than that changed, though? The feel of these two outfits is completely different - one is completely corporate (at least it would be appropriate for the dress code at the hospital where I work, it could be different at your workplace) and the other completely casual.
Even though I usually focus on changing out shoes and bags, especially when I travel, it's worth remembering that bringing two different coats can double your wardrobe possibilities. Might make stuffing that extra coat in your luggage worthwhile!
More pictures and outfit details follow.
Trench coat: Zara, thrifted (similar)
Jacket: Gap, thrifted (similar)
Tee: J. Crew Factory (exact)
Skirt: Old Navy (exact)
Shoes: Nine West, thrifted (similar)
Bag: Ashley Brooke via DSW (similar)
Earrings: vintage Navajo via ebay (similar)