You needed some plants. There you are buying your first plant. Upon purchase, it comes with a tiny white insert in the soil telling you exactly how much water and sun it requires. It even discloses how far to plant it from another plant to optimize growth. You soon discover it needs full sun, plenty of water and as for the spacing...that's irrelevant as it's your only one. You love the new plant, it really spruces up your apartment; you water it; and you make sure it has full sun. Soon, it begins to grow; and bloom; and brings you so much joy that low and behold, you want another one. You run to the store to purchase it; it's slightly different, but close enough. However this time, one innocent yet significant error has occurred: you disregard the plant's tiny white insert in the soil. You toss it; your other plant has done so well that you think why would I need to read that silly card again?! The second plant is placed directly next to the first; it's watered similarly, given sun similarly; but it doesn't grow. Hmmm. What's wrong with this plant? It's alive but not thriving; it's not blooming; it's meek at best and certainly nothing to brag about. What's wrong with it? Nothing. The plant's not the problem; you are. You assumed it was just like the first plant, and it's not.
I know what you're thinking. My children are not plants, and you, sir, are not a botanist. Correct. Two times. I am, however, positioned in a job where I interface with many second siblings flailing through high school suffering from the parenting strategies that yielded remarkable results with the family's first child, but are not suitable for the second. If you know much about the role of an assistant principal you are aware that in large part we interface with students who are disenfranchised, misguided, misunderstood, mildly to convincingly angry, uninspired, lost, behind, and down-and-out. Regardless of what you want to call them or how you want to classify them, they all have something in common: they're trying to get, and most importantly keep, their parents' attention. The underlying issue? They aren't having their needs met; and it's no one's fault. Commonly, neither parent nor child realize that the previously successful methods and systems that propelled the first child into awesomeness are proving futile on the second go around. Hence the anger. The confrontations. The miscommunication.
Back to plants for a second. All plants to some degree require water and light to thrive. Right now in my house I have plants positioned in different areas according to their needs; they all live in my house, but they are not treated the same. The orchid likes to be left almost entirely alone, same with the succulents (but in a different sort of way) and the herbs are needy and high maintenance. I could go on, but you get the point. The same approach needs to be taken into your parenting strategies. Same house, different kids, different needs. A one-sized approach does not work with plants, and certainly is a grave error when raising mentally healthy and vibrant children.
A shift in thinking (may be) required. It's totally normal to compare your children; it has its time, place and life within the realities of parenting. I urge you to recognize comparisons for data's sake, but strongly advise against verbalizing the contrasts directly to your children. For example, I imagine you know which of your children began to walk or talk earlier than the other; but no one remembers (besides you) who did what first; they each got there eventually. I urge you to celebrate your second child for who they are and not for who you were anticipating them to be. Critical life and academic decisions should be driven by maturity and not age or typical hierarchical order. A license may be granted at sixteen but that does not mean every child gets one; and AP Human Geography might be a perfect match for certain 9th graders, but not all. This is particularly important when guiding second siblings through high school; they should not be expected to embrace a particular sport, activity, or lifestyle simply because it was what was done previously by child number one. It is vital to determine who they are, what they like, what inspires them, and what natural limits are in play prior to mandating a prescribed path that is both uninspiring to the student and increasingly painful to the health your relationship. I am not recommending that you let your second child do whatever they want, but I am urging you to let them carve their own slice of the family pie; and do it with their best effort, your full support and within a well-defined family plan. Communication is key. It is the water and sunlight to your relationship and to their success; without it, they will remain meek and frail. Surviving, but not thriving.
Prune as needed. Sometimes plants get too big for their own good, and counter-intuitively we need to prune them to their most basic being in order to ensure long term health; the same is often true with teens. Teens make mistakes, and mistakes need to be addressed. Pruning might be taking the keys to the car, cutting off extra money, isolating them from their friends, implementing drug testing, or making them get a job (the list goes on). Prune away, but do so with caution; prune with clear intent; prune with a logical plan in order to ensure the long term health of your teen. A hopeless teen is a dangerous animal. We don't prune a plant by chopping it down; and we can't take a teen out at the knees and expect them to get back up. Be deliberate with your decisions and be willing to adjust according to the situational need. More than anything else, prune with unconditional love.
There's a reason gardens have more than one kind of plant. Your second child is their own person, their own plant, with unique qualities, needs, likes, strengths, weaknesses, beauty, size, shape, future and so on; treat them as such. If they seem wilted, try moving them to a new window, or adjust their sunlight or water. For the same window that gave your first plant such astounding growth may be unintentionally shading a plant that requires full sun.