Investing.com tells you what the market is doing. PnL App tells you what you tend to do about it.
Investing.com is a broad market data platform, charts, news, an economic calendar, real-time quotes across asset classes. PnL App has none of that. It's a behavioral journal that logs your trades and the emotional state and rule adherence behind each one, focused entirely on your own decision-making rather than market data itself.
PnL App logs the behavior behind every trade, whatever data or news prompted it.