One expresses joy and has good wishes for the new pioneer. The other questions the pioneer’s motives and implies that she is merely seeking prominence in the congregation.
لَا شَكَّ أَنَّكَ لَنْ تَتَحَيَّرَ فِي أَمْرِكَ ،‏ إِذْ مِنَ ٱلسَّهْلِ أَنْ تَعْرِفَ أَيَّةُ وَاحِدَةٍ مِنْهُمَا قَدْ تُشْعِلُ بِحَدِيثِهَا ٱلنَّارَ فِي ٱلْجَمَاعَةِ .‏